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32 Cards in this Set
- Front
- Back
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How many genes are there?
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25,000
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What causes normal genetic variation?
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Single Nucleotide Repeats (SNP)- occurs every 100-500 bps. Occurs in @ least 1% of pop
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What are the types of genetic disorders?
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Single-gene, polygenic, & chrom disorders
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What are the types of single-gene disorders?
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Biochemical, metabolic, & structural defects
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What are the types of polygenic disorders?
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Congenital malformations, diabetes mellitus, & cancer
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What are the types of chrom disorders?
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Multiple birth defects
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What is genotype?
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One's genetic makeup; the allele of a gene that a person carries
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What is phenotype?
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One's observed set of traits or charac
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What are the 3 phenotypic traits?
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Dominant (expressed in hetero & homo), Recessive (only in homo), & Co-dominance (both allels expressed in hetero eg ABO bloof group)
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What is penetrance?
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The proportion of indivd who carry the causative genotype & manifest the disease. Can be age related. Don't confuse w/ variable expression. All or none phenom
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When does reduced penetrance occure?
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When someone w/ abnormal genotype fails to express any features of the disorder
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What is expressivity?
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The degree to which the phenotype reflects genotype
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What is variable expression?
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Differing manifestations in individ w/ the same genotype. Most dramatic fo auto domin conditions
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What is an example variable expressivity?
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Café au lait spot & neurofibromas in NF1
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What is genetic heterogeneity? Types?
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The same phenotype is caused by diff genotypic abnormalities. Allelic & locus heterogeneity
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What is allelic hetero?
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Diff mutations in the same gene may explain variability in expression
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What is locus hetero?
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Mutation in dff genes can lead to a simmilar phenotype
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What is pleiotrophy?
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Diverse phenotypic effects as a result of a single abnormal gene (eg marfan's disease)
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What is anticipation?
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Appearance of inc disease severity or eariler onset in successive generations (trinuc repeats)
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What is Mendel's law of inheritance?
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1) Law of Segregation 2)Law of Independent Asortment 3) Law of Dominance
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What is the Law of Segregation?
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Paired parental genes are separated from ea other during meiosis w/ ea allele seg into separate gametes
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What is the Law of Independent Ass?
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Genes seg into gamets independent of other genes (only if not linked)
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What is the Law of Dominance?
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Distinguishes dominant, recessive & co-dominant traits
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What are the charac of Autosomal dominance?
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Manifests in hetero, every generation affected (vertical exp) , 50% chance affecting offspring,gender affect equally, modified by penetrance & expressivity
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What is spontaneous mutations ass w/?
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Advanced paternal age
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What are the 5 categories of auto dom disorders?
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Problems w/ quantity or arrangement of proteins, reg protiens & receptors, deficiency in proteins that are normally in limited supply, tumor suppressor deletion, mutation makes harmful protein
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What are the prototype auto dom disorders?
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Familial hyperchol & Auto dom polycystic kidney disease
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What causes the plaques in familial hypercholesterolemia?
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single gene mutation. LDL tken up by scavenger pathways by macrophages. Accumulates to form plaques
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What are the clinical features of familial hyperchol?
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Heteros have elevated chol @ birth (350mg/dl), coronary heart disease by 40yo, in homo chol reach 1200 & show atherscol in childhood, & homo die of MI by 30yo
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What are the signs of familial hyperchol?
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Xanthomas, calcified aorta, & MI
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What causes ADPKD?
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2 gene mutation. PKD1 (cell adhesion & signal transduction) or 2 (voltage gated Ca channels). mutation in either 1 causes disease
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What are the clinical features of ADPKD?
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Bilat cysts, kidneys size of footballs by 40yo, 1/2 patients on dialysis or transplanted by 55yo, chronic pain presenting symptom, hypertension is complication in 50% (alters renin-angiotensin)
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