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72 Cards in this Set
- Front
- Back
nature and severity of the phenotype varies from 1 individual to another
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variable expression
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not all individuals with a mutant genotype show the mutant phenotype
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incomplete penetrance
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1 gene has more than 1 effect on an individual's phenotype
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pleiotropy
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differences in phenotype depend on whether mutation is of maternal or paternal origin
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imprinting
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severity of disease worsens or age of onset of disease is earlier in succeeding generations
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anticipation
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mutation in tumor supressor gene, then complementary allele must be mutated before cancer develops
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loss of heterozygosity
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mutation that exerts a dominant effect; heterozygote produces nonfunctional altered protein that prevents normal gene product from functioning
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dominant negative mutation
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tendency for certain alleles at 2 linked loci to occur together; measured in a pop, not a family
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linkage disequilibrium
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occurs when cells in the body have different genetic makeup
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mosaicism
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random X inactivation in females
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lyonization
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mutations at different loci can produce the same phenotye (albinism)
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locus heterozygosity
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what is the heterozygote prevalence according to Hardy-Weinberg equilibrium
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2pq (p,q are separate alleles)
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assumptions of Hardy-Weinberg
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no mutations, no selection, random mating, no migration
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modes of inheritance: due to defects in structural genes (often pleiotropic and presents after puberty)
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AD
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modes of inheritance: often due to enzyme deficiences (often presents in childhood)
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AR
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modes of inheritance: sons of heterozygous mothers have 50% chance of being affected (no male-to-male transmission)
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X-linked recessive
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modes of inheritance: either male or female offspring of affected mother may be affected, while all female offspring of affected father are diseased
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X-linked dominant (hypophosphatemic rickets)
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transmitted only through mother (may affect all offspring of affected females)
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mit inheritance (leber's hereditary optic neuropathy; mitochondrial myopathies)
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AD; always bilateral; massive enlargement of kidneys due to multiple large cysts
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ADPKD
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Presents with pain, hematuria, hypertension, progressive renal failure
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ADPKD
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What chromosome is the mutation in APKD1 on?
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chr 16
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What is APKD associated with?
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polycystic liver disease, berry aneurysms, mitral valve prolapse
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Stupid mnemonic for AD diseases: And Father Marfan Never kNew Timmy Von Hunt Forged His Acent
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ADPKD, Familial hypercholesterolemia, Marfan's syndrome, NF1, NF2, Tuberous Sclerosis, VHL dx, Huntington's dx, Familial adenomatous polyposis, hereditary spherocytosis, achrondroplasia
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elevated LDL owing to defective or absent LDL receptor
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familial hypercholesterolemia (hyperlipidemia type IIA)
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severe atherosclerotic disease early in life, tendon xanthomas (Achilles tendon), MI before age 20
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familial hypercholesterolemia (hyperlipidemia type IIA)
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fibrillin gene mutation
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Marfan's syndrome
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skeletal abnormalities: arachnodactyly, hyperextensive joints, and long, tapering fingers and toes
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Marfan's syndrome
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find dissecting aortic aneurysms and subluxation of lenses, along with skeletal abnl
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Marfan's syndrome
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cafe-au-lait spots, neural tumors, Lisch nodules (pigmented iris hamartomas).
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NF 1
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which chr for NF1?
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17 (17 letters in Von Recklinghausen)
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bilateral acoustic neuroma, optic pathway gliomas, juvenile cataracts
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NF 2
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which chr for NF2?
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chr 22
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adenoma sebaceum, ash leaf spots on skin, cortical and retinal hamartomas, seizures, mental retardation, renal cysts, cardiac rhabdomyomas
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tuberous sclerosis
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hemangioblastomas of retinal/cerebellum/medulla, half get multiple bilateral renal cell ca
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VHL disease
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which chr for VHL disease?
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chr 3 (3 words)
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depression, progressive dementia, choreiform movements, caudate atropy, decreased GABA and Ach in brain, CAG repeats
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Huntington's dx
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Huntington's dx affects which chr
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chr 4
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colon becomes covered with adenomatous polyps after puberty
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familial adenomatous polyposis
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which chr for FAP
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chr 5 (5 letters in polyp)
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spheroid erythrocytes; hemolytic anemia; increased MCHC; splenectomy is curative
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hereditary spherocytosis
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defect in FGFR3
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Achondroplasia
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mnemonic for AR diseases: Crystal And Alfred Put Those Stupid Genes Inside My Stupid Horse
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cystic fibrosis, albinism, alpha-1-antitrypsin deficiency, phenylketonuria, thalassemias, sickle cell anemias, glycogen storage diseases, infant polycystic kidney disease, mucopolysaccharidoses (except Hunter's), spingolipidoses (except Fabry's), hemochromatosis
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AR defect in CFTR gene on chr 7
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Cystic fibrosis
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defective cl- channel, secretion of abnormally thick mucus that plugs lungs, pancreas, and liver
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cystic fibrosis
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recurrent pulmonary infections (Pseudomonas, s. aureus), chronic bronchitis, bronchiectasis, pancreatic insufficiency, meconium ileus in newborns
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cystic fibrosis
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diagnostic for CF
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increased concentration of cl- ions in sweat test
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most common lethal genetic disease of caucasians
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CF
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tx of CF
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N-acetylcysteine
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name 11 AR disorders (hint: FGHO; DHLFBW)
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Fragile X, G6PD deficiency, Hemophilia A and B, Ocular albinism, Duchenne Muscular dystrophy, hunter's syndrome, lesch-nyhan syndrome, fabry's disease, bruton's aggammaglobulinemia, wiskott-aldrich syndrome
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what gene is deleted in duchenne's md
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dystrophin (due to frameshift mutation)
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accelerated muscle breakdown, onset before 5, weakness begins in pelvic girdle muscles and progresses superiorly, pseudohypertrophy of calf muscles, Gowers' maneuver
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duchenne's muscular dystrophy
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dx of muscular dystrophies
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increased CPK, muscle biopsies
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name of disease where mutated dystrophin gene is less severe than duchenne's
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becker's
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defect in FMR1 gene, 2nd most common cause of genetic Mental retardation (behind Down's)
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Fragile X syndrome
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Associated with macro-orchidism, long face with large jaw, large everted ears, autism
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Fragile X syndrome (testes, jaws, ears)
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what is the triplet in Fragile X
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CGG
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Trinucleotide repeat expansion diseases
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Huntington's disease, myotonic dystrophy, friedreich's ataxia, fragile x (may show anticipation)
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7 most common congenital malformations
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heart defects, hypospadias, cleft lip (w/ or w/o cleft palate), congenital hip dislocation, spina bifida, anencephaly, pyloric stenosis
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Name 3 autosomal trisomies; include chromosomes and prevalence
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Down's syndrome (trisomy 21, 1:700), Edward's syndrome (trisomy 18, 1:8000), Patau's syndrome (trisomy 13, 1:6000)
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most common chr d/o and cause of congenital mental retardation
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down's syndrome
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mental retardation, flat facial profile, prominent epicanthal folds, simian crease, duodenal atresia, congenital heart disease (most common is septum primum ASD due to endocardial cushion defects)
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Down's syndrome
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alzheimer's disease in affected people > 35 years old, increased risk of ALL
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Down's syndrome
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causes of Down's syndrome
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95% due to meiotic nondisjunction of homologous chrs, 4% to robertsonian translocation, 1% to Down mosaicism (no maternal association)
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severe mental retardation, rocker bottom feet, low-set ears, micrognathia, congenital heart disease, clenched hands, prominent occiput. Death by 1 y.o.
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Edwards' syndrome
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severe mental retardation, microphthalmia, microcephaly, cleft lip/palate, abnormal forebrain structures, polydactyly, congenital heart disease, death by 1 y.o.
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patau's syndrome
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microcephaly, severe mental retardation, high-pitched crying/mewing, epicanthal folds, cardiac abnormalities
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cri-du-chat syndrome
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cri-du-chat syndrome is due to deletion of what?
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5p
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22q11 syndromes
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cleft palate, abnormal facies, thymic aplasia --> Tcell def, cardiac defects, hypocalcemia due to parathyroid aplasia
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when is highest risk of OH
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3-8 weeks of pregnancy
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developmental retardation, microcephaly, facial abnormalities, limb dislocation, heart and lung fistulas
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fetal alcohol syndrome
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mechanism of fetal OH syndrome
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inhibition of cell migration
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number one cause of congenital malformations in US
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fetal OH syndrome
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