Sex

1) Define pelvic cavity and review its boundaries Lesser/Greater Sciatic Foramen → gluteal region

Obturator foramen → medial thigh Inguinal Ligament → anterior thigh Bladder – most anterior

- abdominal and pelvic structure Uterus (female)

Rectum – most posterior Pelvic Inlet = Pelvic Brim

- Sacral Promontory - Margins of ala - Linea Terminalis - Arcuate line - Pectineal line - Pubic crest Layers - Bony Wall - Musculature - Nerves

- Parietal Pelvic Fascia

- Vessels

- Arteries (medial) - Veins

- Nerves (lateral) - Peritoneum

Greater Sciatic Foramen

- Superior Gluteal nerves/vessels ---Prirformis---

- Inferior Gluteal nerves/vessels - Sciatic Nerve

- Posterior cutaneous nerve of thigh - Nerve to quadratus femoris

- Pudendal nerve → exit pelvis – only sensory - Internal pudendal vessels → exit pelvis - Nerve to obturator internus → exit pelvis Lesser Sciatic Foramen

- Obturator internus

- Pudendal nerve → return into pelvis

- Internal pudendal vessels → return into pelvis - Nerve to obturator internus → return into pelvis

2) Review blood supply and lymphatic drainage of the pelvis and perineum Arteries of Female Pelvis

Internal Iliac a. (anterior branch) → Obturator a.

→ Umbillical a. → Superior Vesicle a. → Uterine a.

- similar to artery to ductus deferens in men - tortuous

- ureter runs under – “water under the bridge” → Ascending branch → uterus

→ Descending branch → cervix and vagina → Vaginal a. → Inferior Vesicle a.

→ Middle Rectal a.

→ Internal Pudendal a. → Inferior Rectal a. → Inferior Gluteal a. – pass between S2 and S3

Internal Iliac a. (posterior branch) – parietal branches – supply posterior wall → Iliolumbar a.

→ Lateral Sacral a.

→ Superior Gluteal a. – pass between lumbar sacral trunk and S1

Arteries of Male Pelvis

Internal Iliac a. (anterior branch) → Obturator a.

***may arise from external pudendal artery

→ Umbilical a.

→ Superior Vesicle a. → Artery of ductus deferens → Inferior Vesicle a.

→ Middle Rectal a.

→ Internal Pudendal a. → Inferior Rectal a. → Inferior Gluteal – pass between S2 and S3

Internal Iliac a. (posterior branch) – parietal branches – supply posterior wall → Iliolumbar a.

→ Lateral Sacral a.

→ Superior Gluteal a. – pass between lumbar sacral trunk and S1

Lymphatics

Inferior Phrenic lymph nodes Lumbar lymph nodes

- Pre-aortic – celiac, superior mesenteric, inferior mesenteric

- Left Lateral Aortic

- Right Lateral Aortic (Caval)

- Retroaortic

Iliac lymph nodes

- Common Iliac

- External Iliac

- Internal Iliac

Inguinal lymph nodes

- Superficial – horizontal, vertical (T-shaped)

Sacral lymph nodes Collateral Circulation in Pelvis Lumbar a. ↔ Iliolumbar a.

Median Sacral a. ↔ Lateral Sacral a. Superior Rectal a. ↔ Middle Rectal a. Inferior Gluteal a. ↔ Deep artery of the thigh Veins of Pelvis

Pelvic Organs → Internal Vertebral (Batson’s) Venous Plexus - cancer can metastasize to brain and spinal cord - cancer can spread to heart and lungs

Lymphatic Drainage

- Fundus of Uterus near Round Ligament – superficial inguinal lymph nodes - Lower Uterine body, Cervix, and Bladder – internal and external iliac lymph nodes - Ovaries, Uterine Tubes, Upper Uterine Body, Testis – para-aortic lymph nodes

- Glands Penis (Clitoris) and Labium minor – deep inguinal and external iliac lymph nodes - Prostate and Lower Rectum – internal iliac lymph nodes

3) Nerves of the pelvis (somatic, autonomic – SNS, PNS) Pelvic Nerves

- Somatic – ventral rami → motor

- Sacral Plexus – Lumbosacral trunk (L4, L5) + S1-S4 - Coccygeal Plexus – S4, S5 + Coccygeal nerves

- Autonomic

- Sacral Splanchnic (Sacral Plexus) – SNS – lower limb

- Pudendal Nerve – S2, S3, S4

- Coccygeal Ganglion (Impar)

- Periarterial Plexus – SNS – vasomotor

- Hypogastric Plexus – pelvic organs

- Superior Hypogastric plexus (SNS) - Right and Left Hypogastric Nerves (SNS)

- Inferior Hypogastric plexus → join pelvic splanchnic (mixed – SNS/PNS)

- Pelvic Splanchnic (Pelvic Plexus) – PNS

- name changes depending on location (ex: prostatic plexus, vesicle plexus, etc.) - Cavernous nerve → supplies penis

Innervation of Bladder

- SNS (T11-L2)

→ contract internal sphincter → relax detrusor muscle - PNS (S2-S4)

→ relax internal sphincter → contract detrusor muscle

4) Concept of the pelvic pain line

*Pelvic Pain Line – corresponds with inferior limit of peritoneum - Above – SNS (T12-L2)

- Below – PNS (S2-S4)

- Large Intestine pain does not correlate with peritoneum - pain line occurs in middle of sigmoid colon

5) Review the innervation of pelvic organs 6) Clinical Correlates

*Suprapubic Cystostomy – drain bladder if urethra is obstructed (ex: enlarged prostate) or injured (torn urethra)

*Pelvic Ultrasound – require full bladder to help sound waves travel better → better visualization of pelvic organs

*Digital Rectal Exam

- Females – palpate Rectouterine (Douglas) pouch - Males – palpate posterior lobe of prostate

*Culdoscopy – insertion through posterior vaginal fornix to examine ovaries or uterine tubes

*Culdocentesis – drainage of pelvic abscess, fluid, or blood through the posterior vaginal fornix

*Anal Reflex – S4, S5

*Anesthesia for Childbirth

- Spinal Anesthesia – lumbar puncture → anesthesia inferior to waist – cannot feel contractions - Caudal Epidural Block – catheter into sacral canal → feel contractions but not pain of childbirth - Pudendal Nerve Block – ischial spine landmark → S2-S4 dermatomes + ¼ of vagina

*Benign Prostatic Hyperplasia – middle/intermediate lobe most commonly enlarged

*Atonic Bladder – L2 injury → detrusor and external sphincter relax, internal sphincter contracted → urine dribble - usually present in early stages of spinal shock

*Automatic Reflex Bladder – reflex contraction every 2-4 hours - loss of voluntary emptying of bladder

*Autonomous Bladder – detrusor flaccid

Bayesian Probability – Adjust a person’s prior risk, most often of being a carrier of a mutant gene

- Conditional Risk – taking into account further information to lower the risk → posterior (modified) risk - ex: unaffected children, negative lab tests, etc.

Prior Risk

Carrier = 1/2

Non-Carrier = 1/2

Conditional Risk – what is the patients risk of being normal? - Age 30 = 10% are clinically affected

Carrier: 9/10

Non-Carrier = 10/10

Joint Risk – (Prior Risk) x (Conditional Risk) Carrier = (1/2) x (9/10) = 9/20 Non-Carrier = (1/2) x (10/10) = 10/20

Posterior Risk – (Joint Risk)/(Sum of Joint Probabilities)

Carrier = (9/20)/(9/20 + 10/20) = (9/20)/(19/20) = 9/20 x 20/19 = 9/19

Non-Carrier = (10/20)/(9/20 + 10/20) = (10/20)/(19/20) = 10/20 x 20/19 = 10/19 Charlotte’s Risk of being a carrier = 9/19

- risk has decrease – originally 1/2, now it is 9/19

Charlotte’s Risk of being having a child with Huntington’s Disease

9/19 [risk of being a carrier] x 1/2 [passing on bad allle] x 99/100 [Penetrance]

= 891/3800

Prior Risk – risk that both Stephan and Kim are carriers/non-carriers Carrier = 1/2 x 1/25 = 1/50

Non-Carrier = 1-1/50 = 49/50

Conditional Risk – what is the patients risk of being normal?

- Both have already had 2 healthy children =  healthy children =  risk Carrier: 3/4 [child 1] x 3/4 [child 2] = 9/16

1/4 = chance of having homozygote recessive

3/4 = chance of being heterozygote or homozygote dominant = unaffected

Non-Carrier = 4/4

- if both are not carriers, what is the risk of their children being affected? Joint Risk – (Prior Risk) x (Conditional Risk)

Carrier = (1/50) x (9/16) = 9/800 Non-Carrier = (49/50) x (4/4) = 784/800

Posterior Risk – (Joint Risk)/(Sum of Joint Probabilities)

Carrier = (9/800)/(9/800 + 784/800) = (9/800)/(793/800) = 9/800 x 800/793 = 9/793  1/88 Non-Carrier = (784/800)/(9/800 + 784/800) = (784/800)/(793/800) = 784/800 x 800/793 = 784/793 Stephan and Kim’s Risk of being carriers = 1/88

Charlotte’s Risk of being having a child with Huntington’s Disease

1/88 [risk of being a carrier] x 1/2 [Kim passing on bad allele] x 1/2 [Stephan passing on bad allele]

Prior Risk – risk that Amelia is a carrier/non-carrier Carrier = 2/3

Non-Carrier = 1/3

- risk of Amelia’s son being a isolated case (1/3) Conditional Risk 1 – what is the patients risk of being normal?

- 70% of DMD carriers show normal CPK levels Carrier: 30% = 3/10

Non-Carrier = 10/10

Conditional Risk 2 – what is the patients risk of being normal?

Carrier: 1/2

- for having a healthy boy

Non-Carrier = 2/2

Joint Risk – (Prior Risk) x (Conditional Risk) Carrier = (2/3) x (3/10) x (1/2) = 6/60 Non-Carrier = (1/3) x (10/10) x (2/2) = 20/60 Posterior Risk – (Joint Risk)/(Sum of Joint Probabilities)

Carrier = (6/60)/(6/60 + 20/60) = (6/60)/(26/60) = 6/60 x 60/26 = 6/26

Non-Carrier = (20/60)/(6/60 + 20/60) = (20/60)/(26/60) = 20/60 x 60/26 = 20/26 Amelia’s Risk of being carriers = 6/26 = 1/13

Amelia’s Risk of being having a child with Huntington’s Disease 1/13 [risk of being a carrier] x 1/2 [passing on bad allele] = 3/26

- if sex is unknown: 3/26 x ½ = 3/52  

1) Describe the important features of the X chromosome, XIC, PAR region Lyon Hypothesis

1) A normal female will only have one X active, the other is inactivated - Barr Bodies – inactive X’s seen in the non-dividing cell

- Dosage Compensation – “Balancing Out” – all X’s in excess of one are inactivated in females → male and females expresses similar doses of most genes on the X chromosome

- ex: factor VIII

- exception: steroid sulphatase; SHOX gene → all in greater amounts in women 2) X inactivation occurs early in embryogenesis

3) Choice of inactivation is random and independent in each cell

4) Inactivation is irreversible and all descendents will have the same X inactivated Manifesting Heterozygotes – A woman is a mosaic of clones with maternal or paternal X’s

- ex: Calico cat – mosaic of black and orange due to X-inactivation Skewed X (Non-Random) Inactivation → not 50/50 inactivation

- ex: inactivate abnormal X more often than normal X to ensure survival

X Inactivation Center (XIC) – where inactivation begins → spread to short arm and rest of long arm Pseudoautosomal Region (PAR)

- distal short arm regions on X and Y chromosomes - contain highly similar DNA sequences

→ allow for crossing-over to take place between X and Y PARs

***Recombination is higher in females than males → genetic map in female is longer than male

- SRY is proximal to PAR1 in Y specific region

- Unequal recombination → XX males (SRY) + XY females (no SRY) 2) Explain the principle of X inactivation

X Inactivation: Molecular Aspects

- X Inactivation Center (XIC) – where inactivation begins → spread to short arm and rest of long arm - Methylation – X Inactivation Specific Transcripts (XIST) → inactivation

- XIST is only expressed in inactivated chromosome → spread inactivation methylation signal - Not all the X is inactivated

if all X chromosome were inactivated → women would all be Turner’s Syndrome!! - Pseudo-autosomal region – gene in that remains active and escape XIST inactivation

- Xp gene > Xq gene

- deletions of Xp → more severe phenotype 3) Explain the consequences of X autosome translocations

X Autosome Translocation

Balanced Translocation → inactive normal X

- derivative X contains important genes due to translocation and needs to be expressed Unbalanced Translocation → inactive derivative X

Reciprocal Balance Translocations

- exchange of genetic information between non-homologous chromosomes

- exchange of genetic information between homologous chromosomes at different sites - Derivative (der) – abnormal chromosome

- 70% of balanced translocations are inherited

- reciprocal translocations are unique to a family

- carriers are usually phenotypically normal but have reproductive problems

→ infertility; miscarriages; children w/abnormal phenotypes or unbalanced translocations - many female carriers of a balanced X-autosome translocation are infertile 4) Explain the genetic basis, molecular and clinical features of Duchenne muscular dystrophy

Duchenne Muscular Dystrophy (DMD)

- X-linked progressive myopathy → muscle degeneration

- most commonly inherited form of muscle disease (1:3500 in males)

Pathogenesis: loss of dystrophin which stabilized smooth, cardiac, and skeletal muscle along with brain neurons

- Dystrophin gene – large gene (3-78 exons) → high mutation rate →allelic heterogeneity

- Allelic Heterogeneity – multiple types of mutations (for DMD gene)

60% = large deletion

5-10% = large duplication

25-35% = small deletions, insertions, point mutations - de novo mutations during Oogenesis and spermatogenesis Isolated Case – new mutation

- 1/3 of DMD are due to new mutations

*Becker Muscular Dystrophy (BMD) – allelic mutation → frame-shift mutations → shorter dystrophin protein Clinical Features

Onset: childhood

- difficulty standings, walking, sitting, climbing stairs (Gower’s maneuvers/sign) - pseudohypertrophy of calf muscles

- IQ one standard deviation below the mean

- DMD will involve heart muscle and respiratory system → death (age 18) Testing

- Creatine Phosphokinase – elevated 10-20 times → indicate muscle damage - Stain for dystrophin protein

Molecular Diagnosis

- Multiplex PCR

- Linkage Analysis

Treatment:

- No cure

- Treatment objective = slow down disease progression and optimize cardiac/pulmonary function 5) Explain the basis of DMD expression in females X autosome translocation

6) Explain the principles of skewed X inactivation in relation to the expression of the DMD in females Duchenne Muscular Dystrophy Expression in Females

- Age of onset + Severity depends upon degree of skewed X inactivation

- ex: if X chromosome carrying DMD allele is active → female develop signs of DMD - 70% of female carriers will have slightly elevated serum creatine kinase

- 20% of female carriers will have some muscle weakness

1) Explain characteristic features of trinucleotide repeat disorders (unstable mutation, anticipation, threshold, gender bias for expansion of the repeat)

Classical Inheritance

Identical inherited mutations – mutation for a genetic disorder is stable from one generation to the other

Trinucleotide Repeat Disorders – Triplet Repeat Disorders

- most common type of unstable dynamic mutation

- trinucleotide repeats  microsatellites (triplets which have no function) Mechanism – slippage mis-pairing

- ex: replication strand detaches inappropriately from template - ex: replicating strands slips from proper alignment → mis-match - ex: extra repeat

Dynamic Mutation – mutation which changes upon transmission - ex: Trinucleotide Repeat Disorders

- expansion in increasing number of three nucleotide repeats

- disease occurs when expansion surpasses a certain threshold

- below threshold – repeat is stable in mitosis and meiosis - above threshold – repeat is unstable in mitosis and meiosis Anticipation

- progressively earlier onset and increased severity in successive generations -  [repeats] → earlier onset + increased severity

2) Examples of disorders associated with trinucleotide expansion (myotonic dystrophy, Fragile X syndrome, Huntington’s Disease)

Myotonic Dystrophy – CTG

-1:8000 – most common heritable neuromuscular disorder

- CTG expansion 5’ end in non-coding region of dystrophy myotonic protein kinase (DMPK) - Extreme variability

- Anticipation

- Differential expansion in maternal and paternal allele

- greater expansion if maternally inherited → congenital form almost always maternally inherited - congenital form rarely from paternal carrying CTG expansion

Normal – 4-37 repeats – none Premutation – 38-49 repeats – none

Protomutation – 50-80 repeats – asymptomatic with mild late onset (cataracts) Mutation – 200-500 repeats – associated with 3rd _{or 4}th _decade

Mutation – 280-800 repeats – childhood onset Mutation – >1000 repeats – congenital

- EMB

- Serum creatine kinase

- Eye exam

- Cannot release handshake

Fragile X Syndrome – CGG/GCC

- Threshold > 200 repeats - Loss of function - Maternal transmission

- 1:4000 (male); 1:8000 (females) – leading cause of inherited mental retardation - FRM1 – hypermethylation → loss of function due to expansion of CGG triplet

→ moderate retardation (males) – IQ 30-50

→ mild retardation (females) – Skewed X inactivation - Onset: childhood

- Pre-Puberty – large head

- Post-Puberty – long head, large ear, prominent jaw, large testis

- Somatic Mosaicism – patients can have a mixture of cells ranging from premutation to full mutation Normal – 6-44 repeats – normal

Gray Zone – 45-58 repeats

Premutation – 59-200 repeats – normal intellect Full Mutation – > 200 repeats

**risk of expansion from premutation to full mutation increases with length of premutation - Full Mutations are mitotically unstable

- Female carriers of premutation are at risk of premature ovarian failure

- Male carriers of expanded, but unmethylated premuation at risk of Tremor/Ataxia Syndrome (FXTAS) - affect mostly men over 50 years old

- Testing

- Southern Blot Analysis

Huntington Disease – CAG

- autosomal dominant - Threshold > 40 repeats - Gain of function - Paternal transmission

- Voluntary and Involuntary movement – chorea (90%) - cognitive abnormalities

- behavioral disturbances

- Avg. age of presentation – 35-44 (25% developed after 50 years old) - Median age of survival – 15-18 years

- CAG repeat in exon 1 coding for polyglutamine → toxic gene product - Anticipation –  expansion → earlier the onset

- expansion > 36 repeats from paternal transmission (more common) Normal – < 26

Mutable – 27-35 – all patients inherit this allele from their father Reduce Penetrance – 36-39

Huntington Disease – > 40 - Anticipation

1) Understand the basis of genomic imprinting Genomic Imprinting

- differential expression of alleles depending on parental origin → homologous chromosomes are not expression equally

→ diseases can result whether a gene is inherited from maternal or paternal origins → methylation – main mechanism by which expression is modified

- Differentially Methylated Regions (DMR) – genes know to be imprinted - Imprinting Control Regions (ICR) – regulation of imprinting

- occur during gametogenesis → maintained through embryogenesis and in somatic tissue - Epigenetic – heritable changes to gene expression that are not due to difference in genetic code - genomic imprinting is erased and reset in the germ line cells for the next generation

2) Know some evidence of imprinting in humans (partial vs. complete moles) Hydatidiform Moles

- molar pregnancy derived from chorionic villi → burrow into uterus - rarely survives to term

Partial Hydatidiform Mole

- 68 chromosomes (46 from father + 23 mother) - Cause: dispermy or endoreduplication

- fetus present but not viable Complete Hydatidiform Mole

- 46 chromosomes (from father) - 46 XX (85%) - 46 XY (15%)

- Cause: fertilization of an empty ovum by 2 sperm or single sperm undergoes endoreduplication - Risk: degeneration into choriocarcinoma (15-20%)

- no fetus present

Differential Expression Trophoblast vs. Embryoblast

- Paternal nuclear genes: embryo fails to develop but trophoblast development proceeds unimpaired - Maternal nuclear genes: embryo will develop but trophoblast development is poor

Conclusion:

- Paternal derived genes essential for trophoblast development - Maternal derived genes essential for embryo development

3) Understand the clinical and molecular basis of and the mechanism of uniparental disomy (UPD) in Prader-Willi Syndrome (PWS) and Angelman Syndrome (AS)

Uniparental Disomy (UPD)

- Non-disjunction @ Meiosis II → uniparental isodisomy (both chromosomes are the same and maternal) - Non-disjunction @ Meiosis I → uniparental heterodisomy (both chromosomes are different but maternal)

- most often leads to PWS *Prader-Willi Syndrome (PWS)

- Phenotypical Features

- Infantile feeding difficulties - Childhood hyperphagia and obesity

- Hypotonia

- Cognitive impairment

- Sterility

- Dysmorphism – abnormal morphologic development

- Mechanisms

1) Interstitial paternal deletion at long arm of chromosome 15 (70-75%)

- 15q11-q13

- deletion cause: illegitimate recombination

- Recurrence Risk: <1%

2) Maternal Uniparental Disomy (25%) → functionally equivalent to a paternal deletion - associated with advance maternal age

→ Maternal heterodisomy

- Recurrence Risk: <1%

3) Chromosomal Abnormality (1%)

- ex: parent with balance translocation → child with unbalance karyotype 4) Imprinting Failure (2%)

- ex: mutation of Imprinting Control Region

→ fail to switch maternal imprints to paternal imprints → fail to express active gene (paternal gene)

- Recurrence Risk: 50%

- Testing: FISH

- Treat: Growth Hormone replacement to normalize height and improve lean body mass - Risk: for additional children with PWS depends on what is the molecular cause of the PWS *Angelman Syndrome (AS)

- Phenotypical Features

- Epilepsy

- Severe learning disabilities

- Unsteady gait

- “Happy face”

- Mechanisms

- 15q11-q13

- Recurrence Risk: <1%

2) Paternal Uniparental Disomy (5%) → functionally equivalent to a maternal deletion - Parental isodisomy – monosomy rescue

- Recurrence Risk: <1%

3) Point Mutation – UBE3A deletion (10%) – ubiquitin gene expressed in the brain

- Recurrence Risk: 50%

4) Imprinting Failure (5%)

- ex: mutation of Imprinting Control Region

→ fail to switch maternal imprints to paternal imprints → fail to express active gene (maternal gene)

- Recurrence Risk: 50%

- Gonadal mosaicism – some eggs may contain the mutation 5) Chromosomal Abnormality (rare)

- ex: parent with balance translocation → child with unbalance karyotype ***Majority of all imprinting disorders are sporadic and not familial!!

1) Understand molecule markers

Locus – particular location on the chromosome (loci) Allele – particular form of a gene

Genetic Markers

- Biallelic marker – RFLP genes encoding for proteins - Minisatellite – VNTR

- Microsatellite – nucleotide repeats - Single Nucleotide Polymorphism (SNP) - Centromere – tandem repeat sequences - Telomeres – tandem repeat sequences Genetic Distance – centiMorgan (cM)

- 1 cM = 1% of recombination frequency (θ = 0.01) - 1 cM = 1 million base pairs (human)

2) Understand polymorphism

Polymorphism – when multiple phenotypes exist in a population of species (ex: hair color) 3) Understand the difference between physical and genetic maps

Physical Map – number of bp

Genetic Map – number of recombinants

4) Understand how to determine the phase using the marker in coupling with the disease

5) Understand what is a recombinant and non-recombinant and be able to calculate (θ) from a pedigree 6) Understand the basic concept of LOD score

Genetic Linkage

Linked – 2 loci closely adjacent on the same chromosome are observed to be inherited together Coupling – linked alleles on the same chromosome

Repulsion – alleles on opposite chromosomes

Linkage Phase – positioning of linked alleles in coupling and repulsion Haplotype – groups of alleles that are coupled

- markers should be numerous and highly polymorphic

 polymorphism increases probability that mating will be informative 1) How far are two loci apart?

- estimate distance by recombination frequency (θ)

θ = (# recombinants)/(Total # of offspring)

- estimate strength b calculating LOD-score - always take the maximal value of LOD LOD-Score = Log10 x (Linkage/No Linkage)

LOD < 1 = suggests two loci are unlinked LOD + 3 and above = proof of linkage LOD – 2 and below = not linked

7) Apply genetic linkage in autosomal dominant/recessive and X-linked conditions Possible Problems

- Do not always know the phase!!

- ex: cannot establish phase in 2 generations = not enough information When Use Linkage?

- if genes responsible for a disease is unknown or you cannot identify known mutations Linkage Disequilibrium – significant deviation (more than by chance) from expected values Linkage Equilibrium – haplotype has frequency of 0.25 in a population

Examples:

θ = 0.05 – chance of recombination (mutation that changes what is expected)

- 5% normal

- 95% affected

θ = 0.05 – chance of recombination (mutation that changes what is expected)

- 5% affected

- 95% normal

Ovary

- 3cm long; 1cm thick; 1.3cm wide

Tunica Albuginea – dense connective tissue – poorly vascularized Germinal Epithelium – simple cuboidal

- give rise to follicular cells

- secrete OMI → arrest development of primary oocyte (diplotene – prophase I) Medullary Region (inner)

- Content: blood vessels and connective tissue Cortical Region (outer)

- Content: ovarian follicles, corpus luteum, corpus albicans Hormonal Overview

GnRH → pars distalis

→ LH → corpus luteum + ovulation + enhance maturation of follicle → FSH → maturation of follicle + ovulation

Secondary + Mature Follicle → Estrogen

Corpus Luteum → Progesterone → receptive for blastocyst (implantation) Primary Follicle

- Primary Oocyte (30μm)

- large nucleus – 1 or more nucleoli + euchromatin

- Balbiani Body – concentrated collection of Golgi membranes, ER, mitochondria, and lysosomes - bursts → release of organelles which multiply in number

- Annulate Lamellae – profiles of nuclear envelope (unknown function) - Cortical Granules – locate beneath plasma membrane

- enzymes alter plasma membrane → prevent second fertilization Growth Primary Follicle – not dependent upon FSH

1) Primordial follicle

- Follicular (granulosa) cells surround follicle; on basal lamina; simple squamous → Filopodia penetrate zona pellucida and contact oocyte via gap junctions

- Zone pellucida – composed of GAG and glycoproteins - Theca folliculi – stomal connective tissue outside basal lamina

2) Unilaminar Primary Follicle – Follicular (granulosa) cells – simple cuboidal 3) Multilaminar Primary Follicle – Follicular (granulosa) cells – stratified cuboidal

- Activin (primary oocyte) → proliferation of follicular layer → Granulosa layer → stimulate FSH release

- Granulosa layer not vascularized Secondary Follicle

- characterized by fluid-filled cavities

- Liquor folliculi = exudate of plasma (GAGs, proteoglycans, steroid-binding proteins, hormones) - Granulosa cells have FSH receptors →  [Granulosa cells] +  intracellular spaces +  [LH receptors]

- Theca Folliculi Differentiates

- Theca interna – inner layer – cuboidal cells - Highly vascularized

- LH receptors → androstenedione (androgen)

- LH receptor expression induced by FSH

- many spaces for lipid droplets

- separated from Granulosa layer via basement membrane

- Theca externa – outer layer

- smooth muscle cells

- collagen fibers

Mature Graafian (Pre-ovulatory) Follicle

- proliferation of granulosa cell and liquor folliculi → single antrum space - Cumulus Oophorus – granulosa cell projection of oocyte into antral space - Corona Radiata – innermost layer of cumulus cells that surrounds oocyte

Summary

1) During Secondary and Mature follicle stage:

LH → stimulate theca interna cells → secrete androstenedione (androgen) FSH → stimulate granulosa cells → convert androgen to estradiol (via aromatase)

→  [estrogen] 2)  [estrogen]

→ negative feedback on FSH at pituitary gland → LH surge

→ resume of meiosis 1 → secondary oocyte + 1st _{polar body} - arrested at metaphase – meiosis 2

→ ovulation (day 14 of 28 day cycle) → formation of corpus luteum

Ovulation

- Surface of ovary loses blood → stigma region (blanched, avascular region)

→ degeneration of stigma region → release of secondary oocyte at distal oviduct (fallopian tube) Corpus Luteum – remnant of Graafian follicle

- temporary endocrine organ

- Corpus hemorrhagicum – central blood clot

- removal of clot by phagocytes under high LH levels → Corpus Luteum - Corpus Luteum

- basal lamina degenerates between granulosa layer and theca interna

- highly vascularized – vessels migrate to Granulosa layer → vascularization of Granulosa layer!

- Granulosa-Lutein cells (80%) – modified granulosa cells - pale-staining (30-50μm)

- secrete progesterone with some estrogen

- estrogen → inhibit FSH → prevent second ovulation

- Theca-Lutein cells (20%) – modified theca interna cells - dark-staining (15μm)

- secrete progesterone with some estrogen

- estrogen → inhibit FSH → prevent second ovulation

- progesterone → inhibit LH

- Corpus Luteum of Menstruation

- lasts 10-14 days

- degenerated Corpus luteum if pregnancy does not occur

→ invade by macrophages/fibroblasts → fibrotic/ceasing of function (Corpus Albicans) - Corpus Luteum of Pregnancy

- lasts 3-4 months

- Human Chorionic Gonadotropin (hCG) – secreted by syncytiotrophoblast

Summary

1) Pulsatile release of GnRH every 90 minutes from arcuate nucleus 2) Development of Follicles independent of FSH

3) Activin stimulates release of FSH → proliferation/stimulation of granulosa cells 4) During Secondary and Mature follicle stage:

LH → stimulate theca interna cells → secrete androstenedione (androgen) FSH → stimulate granulosa cells → convert androgen to estradiol (via aromatase)

→  [estrogen] 5)  [estrogen]

→ negative feedback on FSH at pituitary gland → LH surge

→ resume of meiosis 1 → secondary oocyte (arrested at metaphase – meiosis 2) → ovulation (day 14 of 28 day cycle)

→ formation of corpus luteum

6) Corpus Luteum

- progesterone → inhibit LH

- estrogen + inhibin→ inhibit FSH → prevent second ovulation - all FSH-dependent follicles → atresia

Oviducts (Fallopian/Uterine Tube)

Infundibulum – with fimbriae Ampulla – where fertilization occurs Isthmus – narrow portion

Intramural region – opening into uterus Layers

- Mucosa – extensive folds that project into lumen

- Lamina Propria

- Muscularis

- inner circular smooth muscle

- outer longitudinal smooth muscle - Serosa – composed from mesothelium

- Epithelium:

1) Non-ciliated columnar Peg or secretory cells

- secrete nutritive material for ovum and facilitate capacitation 2) Ciliated columnar cells

- beat towards uterus

Uterus (Fundus and Body)

Endometrium (inner)

Functionalis layer – thick superficial layer sloughed off during menstruation

- Epithelium: simple columnar epithelium – non-cilitated columnar secretory + ciliated columnar

- Lamina Propria: tubular glands extending from basalis layer

- Vascularized – spiral arteries → rich network of capillaries + blood-filled sinusoids Basalis – narrow layer below functionalis layer

- Regenerative layer → regenerate sloughed-off funcionalis layer (glands and connective tissue) - Vascularized: straight arteries (via arcuate arteries in myometrium)

Myometrium

- Muscular Layers (3) – smooth muscle

Inner Longitudinal

Outer Circular (Statum Vasculare) – highly vascularized – arcuate arteries

Outer longitudinal

- muscle amount diminished and is replaced by fibrous connective tissue as you approach cervix → cervix composed of DCT w/elastic fibers and scattered smooth muscle cells

- muscles hypertrophy during pregnancy along with connective tissue (50 → 500μm) Perimetrium

- Fundus + Posterior Body of Uterus = Serosa - Anterior Body of Uterus = adventitia

Cervix

- Epithelium: simple columnar epithelium – mucus secreting

***development of cancer often starts in transformational zone

***epithelium similar to esophagus but no esophageal glands

- Cervical Glands – simple columnar epithelium – cervical glands located below epithelium Ovulation → secrete serous fluid – allow sperm to enter

Normally → viscous secretions → plug at cervix (via progesterone) - Mucosal Lining is not sloughed-off during menstruation

- Relaxin → destroy collagen → cervical expansion (prior to parturition) - Nabothian Cysts – obstructed endocervical glands

Menstrual Cycle

Ischemic Phase – sometimes present depending on textbook!! - Spiral arteries permanently constrict 2 days before day 1 Menstrual (Bleeding) Phase – Day 1 – Day 4

- Spiral arteries permanently constrict 2 days before day 1→ ischemia/necrosis + dilation of spiral arteries → bursting of spiral arteries → discharge of blood that removes functionalis layer

- Functionalis layer is sloughed-off  35 mL blood loss

Proliferative (Follicular) Phase  Day 4 – Day 14

- Renewal of epithelium of endometrium initiated by estrogen

- functionalis layer  2-3 mm thick

- Occurs during same time ovarian follicles are developing Secretory (Luteal) Phase

- Functionalis layer continues to grow (5-6 mm) influenced by progesterone

→ increased vascularity → edema

→ accumulation of glycogen secretions

→ endometrial glands become convoluted and branched

- Implantation

- Stromal cells (C.T. surrounding glands) → Decidual cells – pale and glycogen rich - influenced by progesterone

Vagina

- Epithelium – non-keratinized stratified squamous epithelium (200μm)

- Langerhan cells

- Estrogen → stimulate synthesis and storage of glycogen

- glycogen converted by bacteria to lactic acid as cells are sloughed-off →  pH → anti-microbial

- Lamina Propria

- Loose Connective Tissue → allow for expansion

- highly vascularized

Muscularis

- Inner Circular smooth muscle

- Outer Longitudinal smooth muscle – intermingles with inner circular layer - Sphincter of striated muscle at external opening of vagina

Adventitia – fibroelastic connective tissue

Mammary Glands

- Tubuloalveolar glands

- Lobules → Lobes → Lactiferous duct → Lactiferous sinus - Lactiferous Sinus – dilated portion of lactiferous duct which stores milk

- Milk Content: protein, lipids, lactose, lymphocytes, monocytes, antibodies, fat-soluble vitamins - Lipid Secretion: Apocrine (membrane budding)

- Protein Secretion: Merocrine (exocytosis) Resting (Non-secreting)

- sparse undeveloped alveoli + inactive duct elements

- Epithelium

- Duct: simple columnar epithelium

- Lactiferous Duct/Sinus: stratified cuboidal epithelium

Lactating (active)

- developed alveoli + hypertrophy of breast via estrogen and progesterone

- alveoli surround by myoepithelial cells – influenced by oxytocin → milk ejection - Colostrum – protein-rich fluid; first milk released by mothers

1) Use diagrams to show the fetal membranes and discuss the fate of each (amnion, chorion, yolk sac, and allantois)

Primitive Umbillical Cord

1) Connecting Stalk – Allantois + Umbillical Vessels 2) Yolk Stalk – Vitelline Duct + vessels

3) Canal – connect intraembryonic and extraembryonic cavities Amniotic Cavity

- rapid enlargement → envelopment of connecting stalk and yolk sac → primitive umbillical cord - Amniotic fluid

- absorb jolts

- allows for fetal movement

- prevent adherence

- fluid replaces every 3 hours – fetus swallows its own amniotic fluid

2) Describe the development of the placenta. Use diagrams to show features of placental structure and function

The Placenta

Fetal Portion – chorion frondosum (villous chorion)

Maternal Portion – decidua basalis (functionalis layer of endometrium) Decidua

- Decidua basalis – forms maternal portion of placenta - Decidua capsularis – overlies conceptus

- Decidua parietalis – remaining parts of decidua Tertiary Villus – filled with capillaries and connective tissue Chorionic Villi

- Growth of chorionic villi posteriorly → compression and degeneration of decidua capsularis → smooth chorion (chorion laeve) – avascular bare area

- Growth of chorionic villi anteriorly → growth into decidua basalis → Chorion frondosum (villous chorion)

- 4th _{month – decidua basalis replaced by frondosum} Fetomaternal Junction

- Cytoprophoblastic shell – attach villous chorion to decidua basalis → anchor to chorionic sac

- endometrial vessels pass through shell → open in intervillous (lacunar) spaces via gap junctions - Placenta Septa – decidua basalis that erodes into intervillous spaces → wedge shaped septa

- divide placenta into incomplete cotyledons (compartments)

- intervillous space lined by syncytiotrophoblast ( derived from synctiotrophoblasts) Amniochorionic Membrane – fusion of amnion and smooth chorion

- adhere to decidua parietalis → ruptures during labor → amniotic fluid escape through cervix and vagina 3) Illustrate the placental membrane barrier and discuss the transfer of materials between fetal and

maternal blood Circulation of Placenta

- Endometrial arteries – maternal blood flows into intervillous spaces toward chorionic plate - blood flows slowly over branch villi → gas/nutrient/metabolic product exchange - Endometrial veins – return blood to maternal circulation

Fetal Circulation

- Arterio-Capillary-Venous System – brings fetal venous blood close to maternal blood - Placental Membrane/Barrier – separates maternal and fetal blood → no mixing of blood!!

- Pre-week 20 – 4 layers

1) Syncytiotrophoblast

2) Cytotrophoblast

3) Connective tissue in villous core – extraembryonic mesoderm 4) Endothelium of fetal capillaries

- Post-week 20 – 2 layers → faster exchange

1) Syncytiotrophoblast

2) Endothelium of fetal capillaries

4) List the main activities of the placenta and explain their role in maintaining pregnancy and promoting embryonic development

Function of Placenta

1) Metabolism

- Synthesis: glycogen, fatty acids, cholesterol

2) Transport (simple diffusion, facilitated diffusion, active transport, pinocytosis) - gases, nutrients, electrolytes

- maternal antibodies (week 14) – IgG → passive immunity - newborns reach adult levels at age 3

3) Endocrine Secretion

- Syncytiotrophoblast – proteins and steroids

- Human Chorionic Gonadotropin (hCG) – maintain corpus luteum

- measured to determine pregnancy

- Human Chorionic Somatomammotropin (hCS) – give fetus priority on maternal glucose

- Thyrotropin (hCT)

- Corticotropin (hCACTH)

- Progesterone – maintain corpus luteum

- Estriol – stimulate uterine growth and development of mammary glands - max levels just before end of pregnancy

***Protein hormones do not cross placenta except T4, T3 and Unconjugated steroids

***Drugs can cross placenta via simple diffusion

5) Discuss the effects of drugs, viruses, and microorganisms that can cross the placental barrier *Alcohol

*Organic Mercury *Thalidomide

*Diethystilbestrol – synthetic estrogen – cross placenta → carcinoma of vagina + abnormal testis *Treponema pallidum – syphilis – cross placenta

6) Use diagrams to show the gross and microscopic features of the placenta and umbilical cord 7) Discuss the embryological basis on twins

Dizygotic Twins – fraternal twins – 2 eggs + 2 sperm

Telomere Structure

- Telomere repeats sequence = AGGGTT = GGTTAG = TTAGGG

- always have one repeat unit that is single stranded at the tip of the 3’ strand - triple helix loop stabilized by proteins → protection from degradation Mosaicism – mitotic error → two cells that differ in content or expression

Chimerism – inclusion of cells originating in two different zygotes Euploidy – normal chromosome count

Aneuploidy – abnormal chromosome count

Polyploidy – extra copies of ALL chromosomes → not viable

Trisomy – excess of one chromosome → only Trisomy 13, 18, 21, X, Y are viable

- trisomy 16 is most common → spontaneous abortion

- size and amount of genes on chromosome determines severity - mutation in 18 and 13 → more severe

- 80% of trisomy 21 die in utero

Monosomy – lack of one chromosome → only Monosomy X is viable

- 99% of monosomy X die in utero

Non-disjunctions – primary or secondary meiotic non-disjunctions - primary (maternal) → trisomy

- 2 cells with 1 of each type → trisomy (ex: 1, 3, 7) - 2 cells with nothing → monosomy

- secondary (paternal) → monosomy

- 1 cell with 2 of 1 type → trisomy (ex: 1, 3, 3) - 2 cells with 1 of 1 type → normal

- 1 cell with nothing → monosomy

*Quantitative Marker Analysis – measure with quantitative marker and compare peaks (ex: 1, 3, 3 vs. 1, 3, 7)

Turner Syndrome (Monosomy X) Diagnosis:

- normal intelligence

- short stature

- widely-spaced nipples

- “webbed” neck

- missing development of secondary sexual characteristic

- infertile

Incidence: 1/2500 to 1/5000 females

- defect in paternal meiosis or mitotic error

Complication: Heart Defect (30%); Renal defect (30%); hypertension; and rarely others Ultrasound Findings: Nuchal translucency + heart/renal defects + cystic hygroma - severe defects → spontaneous abortion (99% occurrence)

- Nuchal translucency – space between soft issue of spine and skin - abnormally large (> 95 percentile) indicates abnormality - invisible nasal bone indicates abnormality

Treatment:

- estrogen → induce secondary sexual characteristics - growth hormone → increase height

- remove gonads if virilization occurs Kleinfelter Syndrome (47, XXY)

Diagnosis

- intelligence ranges from normal to mental retardation

- developmental delays

- learning disabilities

- social maladjustment

OR

- Small testis →  [testosterone]

- infertility

- Gynecomastia (55%)

***Test for pituitary gonadotrophins (feedback)

Incidence: 1/1000 males

- 56% extra maternal X

- 44% extra paternal X

- 15% mosaics

Complications: obesity, diabetes, thyroid problems, pulmonary disease

Treatment: androgens → improve virilization, bone density but worsen gynecomastia XXX (47, XXX)

Diagnosis:

- no abnormalities to slight mental deficiency - mental retardation with 48, XXXX or 49, XXXXX Incidence: 1/1000 females

- maternal age effect XYY

Diagnosis:

- Increased height

- Slightly decreased IQ

- Behavioral abnormalities (hyperactivity, ADD, learning disabilities) Incidence: 1/1000 males

Down’s syndrome (Trisomy 21) Diagnosis:

- mental retardation

- specific head, hand, feet shapes

- heart malformation (40%)

- hypothyroidism

- aging: early senility; Alzheimer’s disease (APP gene) 95% = trisomy 21

- ex: 14-21 translocation, 21-21 translocation 1% = mosaic

- 60% are spontaneously aborted + 20% still born = 80% die in utero - ex: 14-21 translocation carrier

- 10% chance of having offspring with Down’s syndrome

*Single incidences occur – often maternal age effect

*Robertsonian translocations can lead to multiple cases in a family of Down’s syndrome Edwards Syndrome (47 XX/XY + 18) – most die within first year

Diagnosis: - Prominent occiput - Malformed ears - Small chin - Heart Defects - Mental retardation

- Hypertonicity – clenched fingers Incidence: 1/8000 (80% females)

- maternal age effect

Patau Syndrome (47 XX/XY + 13) – most die within first year Diagnosis:

- Sloping forehead

- Forebrain defect

- Eye abnormalities

- Cleft lip and palate

- Polydactyly

- Heart defect (88%)

- Mental retardation

- Deafness

Incidence: 1/20000

- maternal age effect

Cri-du-Chat Syndrome (spontaneous deletion of several genes – chromosome 5) – good survival into 30s (Italy) Diagnosis

- distinctive, cat-like cry in babies

- low birth weight

- failure to thrive

- severe retardation

- characteristic faces

Incidence: 1/20000 to 1/50000

- among severely retarded = 1/100 (1%) - deletions variable

- mostly spontaneous

- 10% - reciprocal translocation of parent DiGeorge Syndrome (CATCH-22 or VeloCardioFacial Syndrome)

- many have deletion in chromosome 22

- development problems with 3rd _{and 4}th _{brachial arch} → defects in aortic area of heart

→ hypoparathyroidism → hypocalcemia

→ reduced immune function (thymus hypoplasia) → increased risk of psychiatric disease

*Fluorescence in situ Hybridization (FISH)

- use labeled single probe – only works if you know what you’re looking for - must use control probe to flag desired chromosome

- use chromosome paint – cannot detect inversions and small deletions

*Comparative Genome Hybridization (CGH)

- map out genome and hybridize with patient DNA

- measure hybridization signal → detect variation in concentration of genome in a patient (deletions, etc.) - polymorphic copy number variation – variation within genome concentration in normal population

Chromosomes in Cancer

- many cancers show unstable chromosomes during later profession - ex: non-disjunction; structural changes; de novo translocations - accumulation of mutations → allow for faster cell replication/division - Visible as:

- Aneuploidy

- Homogenously staining regions – genetically identical regions due to cancerous cell replication - Double minutes – excised cancerous regions continue to replicate on its own after removal - Karyotype useful for prognosis and treatment

Philadelphia Chromosome → Chronic Myelogenous Leukemia (CML) - BCR – chromosome 9

- ABL – chromosome 22

- BCR-ABL fusion → BCR product is now under control of an upstream ABL promoter → overproduction of WBCs (lymphocytes)

→ low grade fever, fatigue, night sweats → enlarged spleen

→ sternal tenderness (bone pain) Treatment:

- bone marrow transplant (only cure) - hydroxyurea can alleviate symptoms

- tyrosine kinase inhibitor (imatinib mesylate – glivec/gleevec)

- ABL gene is normally tyrosine kinase receptor → inhibit ABL → stop overproduction

1) Explain why multifactorial traits usually show a bell-shaped phenotypic distribution Bell Curve – bell curve distribution observed in quantitative traits

- Regression Towards the Mean – offspring of extreme values tend to deviate back towards the average - extreme values usually caused by unusual environmental effects are aren’t likely to be repeated 2) Define the term heritability and state its limitations of analyzing the nature-nurture problem Heritability – total variance that is caused by genes

- data comes from comparing:

- monozygotic vs. dizygotic twins - twins that were adopted

- siblings raised together vs. siblings adopted - siblings vs. general population

Concordance – values are similar – based upon relatedness (family, monozygotic vs. dizygotic twin, etc.) Correlation – value of one is associated with a change in the value or the expectation of the other

Look at notes to observe graph vs. table to measure heritability

3) Make semi-quantitative “guestimate” about the heritability of some multifactorial traits based on prior knowledge or data presented

Multifactorial Inheritance – a trait influenced by both genes (plural) and environmental factors Polygenic Trait – trait determined by more than one gene but no environmental factors Liability – combination of good and bad alleles + environment

Threshold Trait – when liability is above a threshold value the person will have the disease Observations

1) Siblings of affected have a higher risk than the general population  affected individuals in a family =  risk of being affected Rule-of-Thumb Risk – for those closely related (1st _degree)

- risk for sibling of an affect = square root of population risk 2) Siblings of an affected person belonging to a more rarely affect sex → higher risk

- if affected person belongs to a more rarely affect sex, person must have more bad alleles - since siblings share 50% of their alleles, these siblings will have higher risk 3) More severe the symptoms → more bad genes/environment → higher risk for siblings 4) Risk decreases rapidly if relationship is less close

Example: Pigmentation

- determined by several (>5) genes → show additive effects - show strong signatures of selection

- ex: SLC24A5 in Africans vs. Europeans

4) Specify the typical effects of the number of affected relatives and of the severity of the disease in an affected relative on the risk of multifactorial disorders

5) Apply the multifactorial threshold model to predict the relative risk to first-degree relatives of patients with a sex-influenced multifactorial disorder

> 50% = linkage < 50% = no linkage

- Sib-Pair Analysis

- only works if parents have both good and bad alleles (must be heterozygote) - chose family with at least 2 affected siblings

- calculate allele sharing in each sib-pair

- average all pairs

- look at linkage

Linkage – loci that are close enough that they segregate together through generations Association – events occur together more often than expected in a current generation

Association in Genetics – a disease and a marker allele that occur together more often than expected

Linkage Disequilibrium – occurrence of specific combination of alleles more frequently than expected by chance - bad allele is found together with a specific marker allele in nearly all people carrying the bad allele

- only present if no crossovers happen

- Association Study – look for marker frequency in affected group - Genome Wide Association Study

6) State the role of teratogens and intrauterine infections in the pathogenesis of congenital malformations

7) Describe the importance of identifiable single-gene effects in multifactorial disorders including autoimmune diseases, type 1 and 2 diabetes, Hirschsprung’s, and Alzheimer.

*Hirschsprung’s Disease – “megacolon” due to failure of migration/differentiation of neural crest cells - male > females (4:1)

- high heritability ( 100%) – polygenic

- RET gene – implicated with dominant mutations - involved in tumors after activating mutations

- involved in Hirschsprung’s Disease after inactivating mutation - involved in development and migration of neural-crest cells - Long Segmental Form

- male  females

- mutations of coding region → complete inactivation of RET - Short Segmental Form

- male > female

- Multifactorial – Chromosome 3, 10, 19

- mutations in enhancer → reduced penetrance → turn down expression of RET *Diabetes Mellitus – Type 1 (IDDM)

- General Population = 0.3-0.5% - Sibling of affected = 6% - Affected Father = 4-6% - Affected Mother = 1-3%

- Monozygotic Twins = 30-50% → not purely genetic!! - Genetic factors

2) Aspartic acid in position 57 of DQ = protective against IDDM

→ DR3/DR4 could serve as marker to non-aspartic acid in DQ region

3) Insulin gene → HLA alleles may not be presented well enough in thymus → auto-immunity - short repeat = increased risk

- long repeat = increased insulin expression in thymus → better immune tolerance - Environmental factors

- Viral infections → trigger immune reaction that cross-reacts with pancreas - ex: Coxsackie B, enterovirus

- anti-Coxsackie B antibodies in 39% of children with IDDM *Diabetes Mellitus – Type 2 (NIDDM)

5-10 X more common than IDDM - Sibling of Affected = 15-40%

- Monozygotic Twins = 90% → high heritability (concordance) → mostly genetic!! - Genetic Factors

TCF7L2 – transcription factor → insulin secretion = 1.5X risk

PPAR-γ – transcription factor → adipose/glucose metabolism = 1.25X risk KCNJ11 – potassium channel → insulin secretion = 1.2X risk

- Environmental Factors

- Obesity; low birth weight; diet, activity, etc.

*Diabetes Mellitus – Maturity-Onset Diabetes of the Young (MODY) - autosomal dominant with 80-95% penetrance

- 5% of all diabetes cases

- multifactorial – 7 known genes (glucokinase)

- often misdiagnosed as type I

- Onset:

< 25 years old

- often not obese

- metabolic syndrome is absent Obesity

- major influence of environment

- high concordance

- Leptin; NPY; melanocortin 4-receptor *Alzheimer’s Disease

- formation of amyloid plaques and neurofibrillary tangles - Genetic Factors

1) Amyloid Precursor Protein (APP)

- cleavage by -secretase → Aβ40 and Aβ42

→ overproduction → amyloid plaques and neurofibrillary tangles - Presenilin-1 and Presenilin-2

- mutations → increased cleavage →  [Aβ40 and Aβ42] 2) ApoE4

- Homozygote = 15X risk

- Heterozygote = 3X risk

3) Interleukin-1

- overexpression of IL-1 correlated with plaque formation

- involved in inflammation

- Race

- higher incidence in African American and Hispanic communities (genetic or environmental) *Down’s Syndrome

- APP gene located on Chromosome 21

→ mutations of APP →  [Aβ40 and Aβ42] - ABCG1 gene on Chromosome 21 also suspect

*Cancer – best considered multifactorial with low heritability (majority) *Congenital Malformation

- genetically heterogenous group

- causes:

- genetics (chromosomal abnormalities)

- environment (drugs, infection, nutrition, maternal conditions, etc.)

- single gene disorder

*Pyloric Stenosis - Male > Females

- Increased risk for sibling or children of affected female

- for female to be affected, needs greater amount of defective genes *Mental Retardation

- IQ < 70

- Global Developmental Delay – retardation < 5 years old - multifactorial (genetic and environmental)

- Risk Factor: high maternal age, low education *Schizophrenia

- Concordance = 60-85% for monozygotic twins - Risk Factor: high paternal age

*Bipolar Affective Disorder

- Concordance = 79% for monozygotic twins - no specific genes identified

*Treatment of Coronary Heart Disease and Stroke - multifactorial

- test for CYP2Cp and VKORC1 before starting treatment to improve accuracy of initial drug dosage 8) Describe the major/minor gene alleles have for risk assessment in disease where they occur and state

examples of each in Hirschsprung’s and Alzheimer. Minor Genes – additive effects

Major Genes – act as a dominant allele which will confer  risk - observe Mendelian inheritance

Additive Model – mixing of one gene between two different populations - looks similar to selective distribution

- effects of each allele are co-dominant and have same level of influence on the trait Dominant Model – mixing of one gene between two different populations

1) State the criteria for a valid Hardy-Weinberg equation Rules:

1) Valid for population in equilibrium – allele frequency will stay the same in following generations 2) Mating must be random

3) Consanguinity (incest) – would not change allele frequencies - but proportion of homozygotes would increase 4) New mutations and selection offset each other 5) Population should be large

- offset genetic drift - more genetic variability

- decreased frequency of bad alleles 6) No gene flow (migration)

2) Use Hardy-Weinberg to predict allele frequency and frequency of different genotypes for single gene disorders if the disease incidence is known

Hardy-Weinberg Equation

When having a number of actual people, could alleles instead of using Hardy-Weinberg!!

p

+ 2pq + q

= 1

p2 _{= homozygote dominant}

2pq = heterozygote frequency (carrier frequency)

q2 _{= homozygote recessive (incidence)}

p = 1-q

Review Semester 1 Pedigree

***In autosomal-recessive disorder

- sibling of affected = 2/3 chance of passing on defective gene

***For X-linked recessive

- males have a greater chance of being affected = multiply by ½ q = incidence in males

q2 _{= X-linked recessive}

(affected females)

2pq = X-linked dominant (affected females)

3) Predict the effects of inbreeding and incest on the incidence of autosomal recessive and multifactorial disorders. State legal status of incest in related in part to these expected effects Effects of Small Interbreeding Population

Autosomal Recessive:

→ increased frequency of homozygous affected for recessive diseases → increased selection against bad alleles (long-term effect)

Multifactorial:

→ increased number of affected → decreased intelligence

Monozygotic Twins = share 100% of alleles

First degree Relatives = 50% of alleles (ex: siblings, offspring, parents, etc.) →  30% incidence of severe mortality and mortality

Second degree Relatives = 25% of alleles (ex: half-siblings, uncles, grandparents, etc.) →  3% incidence of severe mortality and mortality

Third degree Relatives = 12.5% of alleles (ex: first cousins, etc.) →  1% incidence of severe mortality and mortality

Interbreeding Coefficient – percentage of gene loci that are homozygous as a result of interbreeding

4) Describe the expected effects of negative selection of allele frequencies of autosomal recessive and dominant diseases, and state that the lack of effects makes negative eugenetic unethical and scientifically wrong

Complete Selection – when a person does not have viable offspring

Even if implemented, it would not really work. It would take 10 generations to have 25% of the population having the gene and probably many more to get it to a smaller percentage.

5) Define the term stabilizing, disruptive, and directional selection. Give examples of each Selection Types

- Stabilizing

- extreme phenotypes do not perform as well → narrowing of distribution towards median

- ex: blood pressure

- Directional

- one extreme of phenotypes performs better → movement of distribution towards one extreme - ex: higher education in women

- Disruptive

- extremes phenotypes do well, but average does not do well → split into two sub-populations - ex: birds at Galapagos Islands

6) Define heterozygote advantage, genetic drift, founder effect, assortative mating Founder Effect

- can only include diseases with a low mutation rate

- isolated population which descends from a small group of people who harbor an otherwise rare mutation → increased occurrence of a otherwise rare mutation within this isolated group

- ex: Afrikaners (variegate Porphyria)

- ex: Old Order Amish (Ellis-van Creveld syndrome), - ex: Pingelap islanders (Achromatopsia 3)

Assortative mating – actively chosen mating

Heterozygote Advantage – heterozygote genotype has a higher fitness than either homozygote dominant/recessive \

7) State the effects of paternal age on rate of point mutations Mutations

- Point Mutations increases with paternal age

1) Age-dependence on infertility and specific causes Infertility – no pregnancy after trying for a minimum of 1 year

- Prevalence: <10% of young couples; more common with increased age

- Cause:

Males: infections, autoimmune, Klinefelter, single gene, Y-chromosome microdeletions; age Female: age; polycystic ovaries, endometriosis, tubal obstructions

- peak fertility at age 22

Female Fertility – normally 20-25% change of pregnancy in 1 cycle

Major Risk: multiple pregnancies

2) Principles, applications, and procedures of sperm banking and donor insemination

Donor Insemination

Procedure: sperm bank → select donor → order frozen sperm → thaw → inseminate Sperm Banks

- Analyze sperm: quality, infectious disease - Educational/psycho-history of donor - Family history of donor

- Carrier tests

3) Principles, applications, and procedures of IVF and ICSI

Intravenous Fertilization (IVF)

Indication: tubal disease (obstruction), or other causes of infertility Procedure:

- done in specialized clinics

1) Induce superovulation – gonadotropins, clomiphene, aromatase inhibitors

2) Harvest eggs

3) Add sperm

4) Incubate 2-3 days

5) Implant 2-6 embryos

- implantation dependent upon age of female  age =  quality of egg →  implantation amount  age =  quality of egg →  implantation amount Outcome

- Success dependent upon age of mother or oocyte donor

< 38 = 36%

> 40 = 11%

Risks: multiple pregnancies (twins – 22%; triplets – 1.1%) Oocyte Donation: $4200 per egg

Cryopreservation

- freezing can damage living cells (ex: osmotic stress, ice crystals piercing membranes) - only possible with small tissue sample (organs or bodies are impossible)

- sperm can be frozen but insemination success is less than with fresh sperm - egg can be frozen without major risks

- oocytes are difficult to freeze Technique:

1) Add antifreeze 2) Rapid freezing

Intracytoplasmic Sperm Injection (ICSI)

- low sperm count - poor sperm quality - immotile sperm

- post-vasectomy

Procedure

- sperm is immobilized → sucked into needle → injected directly into egg cytoplasm during IVF Risk:

Slight increased risk of Beckwith-Wiedeman (overweight fetus) Slight increased risk of Angelman syndromes (imprinting error)

4) Principles, applications, and procedures of pre-implantation genetic diagnosis

Pre-Implantation Genetic Diagnosis

- diagnosis of genetic diseases in early embryo Procedure

- Make IVF

- Grow embryo to 8-cell stage - Remove 1-2 cells for testing

- Single-gene disorder: PCR

- Aneuploidy: FISH

- Shotgun screening – whole-genome amplification and DNA microassays 5) Major risks of procedures for assisted reproduction

Androgens

- Replacement therapy in male hypogonadism

- establish normal puberty and then support male secondary sex characteristics - induce fertility with gonadotropins

- Not effectively administered orally

- high rate of hepatic metabolism → insufficient testosterone levels - oral formulations are hepatotoxic

- non-scrotal patch

- scrotal skin – high rate of DHT conversion →  [DHT] →  BPH risk

- Not effective for primary hypogonadism (problems with testes) - lipid solubility

→ depot preparation – few complications

→ gel preparation – applied daily with attention to bathing and possible contact with others → patch preparations – must be changed once or twice daily; possible skin irritation

Testosterone

1) Begin with low dose

→ stimulate skeletal growth and secondary sex characteristic → avoid premature epiphyseal closure

2) Gradual increase until maturity achieved 3) Establish lifelong regimen

Testosterone Enanthate – Testosterone Ester

- fatty acid-esterification → increase lipid solubility - depot IM injection to bypass enterohepatic circulation

17-Alkylated Androgens

- oral formulation of androgens - hepatotoxic

Drugs to Block Androgen Activity

Flutamide – Receptor Inhibitors

- used in conjunction with Leuprolide → prevent disease flare at initiation of leuprolide

Finasteride – 5-Reductase Inhibitor

- Use: androgen-dependent hyperplasia (BPH)

→ blocks formation of androgen that supports prostate growth and hyperplasia

Gonadotropin-Related Drugs

Leuprolide – GnRH Agonist

- down regulate GnRH receptor →  [androgens]

- “chemical castration”

- use in conjunction with flutamide

Abarelix – GnRH Antagonist

- GnRH receptor antagonist →  [androgens]

- “chemical castration”

Bromocriptine – dopamine agonist

- inhibit prolactin → treat hyperprolactinemia

Treatments of Infertility

Hypothalamic

GnRH

- not currently available

- administration – pump → mimic in vivo pulsatility - lower incidence of multiple birth

Pituitary

- suppress endogenous gonadotropins with GnRH - administer exogenous gonadotropins

Ovarian

Clomiphene – anti-estrogen

- block negative feedback that decreases hypothalamic pulsatility →  [LD] +  [FSH]

Contraception

Adverse Effects

- high doses of estrogen →  clotting factors

- smoking → hypercoagulability

- obesity →  risk of venous thrombosis Combined Oral Contraceptives

- Smokers > 35 years old contraindicated

Estrogens

Estradiol (17β-estradiol)

- micronized for sufficient surface area for rapid absorption → highly absorbed through epithelial surfaces → cleared rapidly after oral administration

Mestranol – metabolized to ethinyl estradiol

Ethinyl Estradiol – more resistant to hepatic degradation

Progestins

- rapid first-pass metabolism → poor bioavailability = give in high doses