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Medical Genetics Exam 1
exam 1
32
Medical
Not Applicable
10/11/2005

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Term
Compound heterozygote
Definition
an individual with 2 different mutant alleles at the same locus
Term
Pleiotropy
Definition
a single gene has diverse effects on multiple organ systems
Term
Locus heterogeneity
Definition
similar phenotypes caused by mutations at DIFFERENT genetic locations
Term
Allelic heterogeneity
Definition
similar or identical phenotypes caused by different mutant alleles at the same locus
Term
Phenocopy
Definition
a condition which is due to environmental factors, but resemebles one that is genetic
Term
penetrance
Definition
proportion of heterozygotes for a dominant gene who express the trait
Term
variable expressivity
Definition
the spectrum and severity of phenotypic features associated wth a particular disorder
Term
clinical features of Marfan syndrome
Definition
tall, thin, scoliosis, pectus, long fingers, myopia, dislocated lenses, aortic dilation, dissections, aneurysms, mitral valve prolapse
Term
etiology of Marfan syndrome
Definition
disorder of fibrillin, mutation in FBN1 gene, most are family specific (no common mutations), autosomal dominant
Term
clinical features of Neurofibromatosis-1
Definition
cafe au lait macules, neurofibromas, plexiform neuromas, lisch nodules, learning disabilities, ADHD, increased tumor risk
Term
etiology of neurofibromatosis-1
Definition
mutations in NF1 tumor suppressor gene, autosomal dominant
Term
clinical features of achondroplasia
Definition
short, large heads, 100% penetrance
Term
etiology of achondroplasia
Definition
point mutation in FGFR3, paternal age effect, new mutation rate 80%, autosomal dominant
Term
clinical features of hemochromatosis
Definition
excess Fe absorption in GI tract, heart failure, cirrhosis, diabetes, hormone deficiency, bronze skin
Term
etiology of hemochromatosis
Definition
high carrier frequency, mutation in HFE gene, autosomal recessive
Term
lyonization
Definition
female mosaicism due to x-inactivation
Term
clinical features of duchenne muscular dystrophy
Definition
early onset, non-ambulatory teens, 1/3 have cognitive delays, cardiomyopathy
Term
etiology of duchenne muscular dystrophy
Definition
many new mutations in dystrophin gene, large deletions in 2/3 pts, mutation often in spermatogenesis in grandfather, x-linked recessive
Term
clinical features of G6PD deficiency
Definition
neonatal jaundice, hemolytic anemia, environmental precipitants: druges, illnesses, fava beans, resistance to falciparum malaria in heterozygotes
Term
etiology of G6PD deficiency
Definition
enzyme deficiency in pentose-phosphate shunt, x-linked recesseive
Term
clinical features of OTC
Definition
urea cycle defect, vomiting, lethargy, coma, hperammonemia
Term
leptotene
Definition
chromosomes become visible as they start to condense
Term
pachytene
Definition
each pair of homologous chromosomes known as a bivalent, becomes tightly coiled and crossing-over occurs
Term
zygotene
Definition
homologous chromosomes align directly opposite each other in a process called synapsis and are held together by synaptonemal complexes
Term
diakinesis
Definition
separation of homologous chromosome pairs as chromosomes become maximally condensed
Term
diplotene
Definition
homologous recombinant chromosomes begin to spearate but remain attached at the point(s) where crossing over occurred
Term
LaZy People DIP and DIe
Definition
5 stages of crossing-over/recombination in meiosis
Term
Leber's hereditary optic neuropathy (LHON)
Definition
first mitochondrial disease indentified; central loss of vision secondary to optic nerve degeneration between 12 and 30 years of age
Term
MERRF
Definition
myoclonic seizures, muscle weakness, dementia, short stature, episodic vomiting, mitochondrial inheritance
Term
MELAS
Definition
mitochondrial myopathy, seizures, mental retardation, lactic acidosis, stroke-like episodes, short stature, repeat vomiting
Term
KSS (Kearns-Sayre syndrome)
Definition
spectrum of disease involving paralysis of eye muscles, cardiac arrhythmias, lactic acidosis, myopathy, mitochondrial
Term
Leigh syndrome
Definition
subacute necrotizing encephalomyelopathy
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