Genetics Flashcards
Barr body in Klinefelter’s is what?
Inactivated X-chromosome
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.
Gene and chromosome affect in familial adenomatous polyposis
APC gene Chromosome 5 (5 letters in “polyp”)
Trisomy of what in Patau syndrome
13 (Puberty at 13)
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.
Genetic defect in Cri-du-chat
Microdeletion of the short arm of chromosome 5
Inheritance and chromosome affected in neurofibromatosis type 1 (von Recklinghausen)
AD Chromomosome 17 (17 letters in “von Recklinghausen”)
Ataxia, spider angiomas (telangiectasias), IgA deficiency (increased sinopulmonary infections)
Ataxia-telangiectasia
What does the Rb gene normally do
Inhibits E2F which blocks the G1 to S transition in the cell cycle
Normal function of frataxin
Mitochondrial functioning
Degeneration of what in freidrich ataxia
Posterior column and spinocerebellar tracts
Osler-Weber-Rendu (aka hereditary hemorrhagic telangiectasia) inheritance
AD
Chromosomal abnormality in Klinefelter’s
XXY
Telangiectasias, epistaxis, AVMs, skin discolorations
Hereditary hemorrhage telangiectasia (aka Osler-Weber-Rendu syndrome)
Increased incidence of what type of brain tumor in tuberous sclerosis
Astrocytoma
Renal complications in tuberous sclerosis
Renal angiomyolipoma, renal cysts
Dysfunctional gene in Friedrich ataxia
Frataxin
Chromosomal defect in turners
XO; hugs and kisses (X’s and O’s) from Tina Turner
Edwards syndrome is a trisomy of what
Chromosome 18 (Election age is 18)
Macro-orchidism (large balls), long face and long jaw, large everted ears, autism
Fragile X syndrome (X-tra large things; balls, face, ears)
If someone has familial retinoblastoma, what other tumor are they most likely to develop
Osteosarcoma
Labs in Turner syndrome
Decreased estrogen leading to increased LH and FSH (loss of negative feedback)
Inheritance, gene and chromosome affected in CF
AR CFTR gene (mostly deletion of Phe at 508) Chromosome 7
Why is dystrophin being the longest gene relevant to it’s genetics
Longer gene=more opportunities for mutations and thus a higher mutation rate
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
AD
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
AD
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
AD
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
