Genetics Flashcards by Joseph Barbato

Barr body in Klinefelter’s is what?

Inactivated X-chromosome

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Bilateral absence of the vas deferens is suggestive of what inherited disease.

Cystic fibrosis; thus, CF can also present as infertility (due to azoospermia) in males. So, both CF and Kartagener’s can present with recurrent respiratory infections and infertility in males. Don’t jump to conclusions.

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Gene and chromosome affect in familial adenomatous polyposis

APC gene Chromosome 5 (5 letters in “polyp”)

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Trisomy of what in Patau syndrome

13 (Puberty at 13)

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What needs to happen in a kid with a familial retinoblastoma disorder to develop cancer.

Sporadic mutation in the normal gene. Both genes need to be affected for cancer to develop; this is the 2 hit hypothesis. If only one gene is affected, the other gene can make up for the mutated gene. However, when a mutation happens to the second gene, then cancer develops.

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Genetic defect in Cri-du-chat

Microdeletion of the short arm of chromosome 5

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Inheritance and chromosome affected in neurofibromatosis type 1 (von Recklinghausen)

AD Chromomosome 17 (17 letters in “von Recklinghausen”)

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Ataxia, spider angiomas (telangiectasias), IgA deficiency (increased sinopulmonary infections)

Ataxia-telangiectasia

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What does the Rb gene normally do

Inhibits E2F which blocks the G1 to S transition in the cell cycle

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Normal function of frataxin

Mitochondrial functioning

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Degeneration of what in freidrich ataxia

Posterior column and spinocerebellar tracts

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Osler-Weber-Rendu (aka hereditary hemorrhagic telangiectasia) inheritance

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Chromosomal abnormality in Klinefelter’s

XXY

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Telangiectasias, epistaxis, AVMs, skin discolorations

Hereditary hemorrhage telangiectasia (aka Osler-Weber-Rendu syndrome)

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Increased incidence of what type of brain tumor in tuberous sclerosis

Astrocytoma

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Renal complications in tuberous sclerosis

Renal angiomyolipoma, renal cysts

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Dysfunctional gene in Friedrich ataxia

Frataxin

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Chromosomal defect in turners

XO; hugs and kisses (X’s and O’s) from Tina Turner

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Edwards syndrome is a trisomy of what

Chromosome 18 (Election age is 18)

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Macro-orchidism (large balls), long face and long jaw, large everted ears, autism

Fragile X syndrome (X-tra large things; balls, face, ears)

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If someone has familial retinoblastoma, what other tumor are they most likely to develop

Osteosarcoma

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Labs in Turner syndrome

Decreased estrogen leading to increased LH and FSH (loss of negative feedback)

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Inheritance, gene and chromosome affected in CF

AR CFTR gene (mostly deletion of Phe at 508) Chromosome 7

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Why is dystrophin being the longest gene relevant to it’s genetics

Longer gene=more opportunities for mutations and thus a higher mutation rate

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Mental retardation, rocker-bottom feet, micropthalmia, CLEFT LIP/PALATE, HOLOPROSENCEPHALY, POLYDACTYLYL

Patau's syndrome (All caps for findings that differ from Edwards syndrome)

Heart defects in Turner's

Bicuspid aortic valve (most common), preductal coarcation of the aorta

Short limbs, large head, normal torso

Achondroplasia

Hemangiomas in the retina/cerebellum/medulla and pts often develop bilateral renal cell carcinoma

von Hippel-Lindau dx

Conjunctivitis, urethritis, and arthritis are the triad of what? Associated with what HLA?

Reactive arthritis triad (can't see, can't pee, can't climb a tree); Mostly associated with HLA-B27

High-pitched "mewing", mental retardation, microcephaly, epicanthial folds, cardiac abnormalities (VSD)

Cri-du-chat (Cry of the cat=mewing)

Cardiac findings in tuberous sclerosis

Cardiac rhabdomyoma

Cardiovascular defects associated with ADPKD

Berry aneurysms, mitral valve prolapse

Hereditary spherocytosis inheritance

Freidrich's ataxia trinucleotide repeat

GAA

Lab values in Klinefelter's

Increased FSH (due to decreased inhibin from seminiferous tubules), and increased LH and estrogen (due to decreased testosterone as a result of abnormal Leydig cell function)

Short, ovarian dysgenesis, shield chest, webbing of neck (cystic hygroma).

Turner Syndrome

Inheritance, gene and chromosome affected in von Hippel-Lindau dx

AD VHL gene deletion Chromosome 3 (3 letters in "VHL")

Myelogenous disorder associated with Down Syndrome

AML

Cafe-au-lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas), skeletal disorders (scoliosis) and optic pathway gliomas

Neurofibromatosis type 1 (von Recklinghausen dx)

Most cases of Down syndrome are due to what

Meiotic nondisjunctin in meiosis 1 (95%) Next most common cause is Robertsonian translocation (4%) Finally, 1% of cases are due to mosaicism

Trinucleotide repeat in Fragile X

CGG

GI defects associated with down syndrome

Duodenal atresia, Hirschsprungs disease

Familial hypercholesterolemia defect due to what?

Defective or absent LDL receptors

Weakness in pelvic girdle muscles, pseudohypertrophy of calf muscles, cardiac myopathy

Duchenne's muscular dystrophy

You find a grown-ass man with bilaterally enlarged kidneys and cysts in his liver

Autosomal-dominant polycystic kidney disease

Adenomatous polyps start developing after puberty

Familial adenomatous polyposis (FAP)

How do newborns often present with CF

Meconium ileus (green poo causing a GI obstruction)

Facial adenoma sebaceums, hypopigmented "ash-leaf" spots, cortical and retinal hamartomas, seizures, mental retardation

Tuberous sclerosis

"Elfin" facies, mental disability, hypercalcemia (increased sensitivity to "the D"), well developed verbal skills, extreme friendliness with strangers

Williams syndrome (Williams the friendly elf)

Inheritance and chromosome affected in Marfan's

AD Chromosome 15 (Mar"fifteen")

Inheritance, gene, and chromosome affect in NF2

AD Chromosome 22 NF2 gene Everything is 2 in this dx; bilateral (2) acoustic neuromas, NF2 gene, chromosome 22 affected

Familial hypercholesterolemia inheritance

Rheumatoid arthritis is associated with what HLA?

HLA-DR4

Mental retardation, rocker-bottom feet, micrognathia (small jaw), low set Ears, clenched hands, prominent occiput

Edwards syndrome

700+ mg/dL cholesterol, tendon xanthomas, early atherosclerotic disease

Familial hypercholesterolemia (hyperlipidemia type IIa)

Heart defects in Down Syndrome

Ostium primum ASD, endocardial cushion defects

Inheritance of tuberous sclerosis

Eye defect in NF2

Juvenile catacts

A kid with a family history of tumors develops a white tumor in his eye that needs enucleated. What gene is affected?

Loss of function in the Rb gene, a tumor suppressor (kid has retinoblastoma)

Gene defect and chromosome affect in ADPKD

Mutation in PKD1 Chromosome 16 (16 letters in "polycystic kidney")

Defect in ataxia-telangiectasia

ATM gene which codes for DNA repair enzymes DNA hypersensitivity to radiation

How does the VHL gene deletion cause hemangioblastomas in von Hippel-Lindau

Cause constitutive expression of hypoxia inducible factor 1 (HIF1) which leads to increased expression of angiogenic growth factors

Most common mutation causes what in CF

Abnormal protein folding leads to the protein being degraded before it reaches the membrane surface

Lab values in Edwards syndrome

Decreased AFP, B-hCG, estriol, and normal inhibin

Inheritance and gene defect in achondroplasia

AD Cell signalling defect of fibroblast growth factor (FGF) receptor 3

Lab values in Patau's syndrome

Decrease B-hCG and PAPP-A, increased nuchal translucency

Male with testicular atrophy, eunuchoid body shape (pear shaped?), tall, long extremeties, gynecomastia, female hair distribution

Klinefelter's syndrome

Cardiovascular problems in Marfan

Cystic medial necrosis leading to aortic aneurysm/incompetence Dissecting aortic aneurysms Floppy mitral valves

2 reasons tuberous sclerosis presents differently or might not present at all

Incomplete penetrance and variable expression

Trinucleotide repeat in myotonic dystrophy

CTG

Defect in spectrin or ankyrin causes this

Hereditary spherocytosis

Ataxia, pes cavus, hypertrophic cardiomyopathy, kyphoscoliosis; disease and inheritance

Freidrich ataxia; AR

How do you diagnosis Duchenne muscular dystrophy?

Increased CPK and muscle biopsy

Kidney defect in Turner's

Horseshoe kidney

Muscle weakness in extremeties, v-shaped upper lip, autosomal dominant

Myotonic muscular dystrophy

Down syndrome is associated with what heart defects

Endocardial cushion defects (ostium primum ASD) and regurgitant AV valves

Inheritance and gene affected in Duchenne muscular dystrophy

Dystrophin gene (frameshift mutation, DMD, longest human gene) X-linked

Trinucleotide repeat in Friedrich ataxia

GAA

Cardiac problem in Fragile X

Mitral valve prolapse