Flashcards in More genetics Deck (76)
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1
What is codominance?
Both alleles contribute to the phenotype
2
What is variable expressivity?
Phenotype varies among individuals with the same genotype
3
What is incomplete penetrance?
Not all individuals with a mutant genotype show the sme phenotype
4
What is pleiotropy?
One gene contributing to multiple phenotypic effects
5
Musty body odor = ?
PKU
6
What is the loss of heterozygosity?
Two hit phenomenon
7
What is a dominant negative mutation?
A heterozygote produces a nonfunctional altered protein that also prevents the normal gene product functioning
8
What is linkage disequilibrium?
Tendency for certain alleles at 2 linked loci to occur together more often that expected by chance
9
What is locus heterogeneity?
Mutations in the same locus produce a similar phenotype
10
What is allelic heterogeneity?
Different mutations in the same locus produce the same phenotype
11
What is heteroplasmy?
Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease
12
What is uniparental disomy?
here an offspring receives 2 copies of a chromosome from 1 parent, and no copies from the other.
13
What does heterodisomy (a uniparental disomy) result from?
Meiosis I error
14
What does isodisomy (a uniparental disomy) result from?
Meiosis II error
15
What is the Hardy-Weinberg equation?
= {p^2 + 2pq + q^2 : p and q are the frequencies of separate alleles}
16
What are the four assumptions made in the Hardy-Weinberg equation?
1. No mutation
2. Natural selection is NOT occurring
3. Random mating
4. No net migration
17
What is imprinting?
Methylation of a certain set of genes, causing silencing
18
What is the cause of Prader-willi syndrome?
Paternal gene deleted on 15q
19
What is the cause of Angelman syndrome?
Maternal gene deleted on 15q
20
What are the symptoms of Prader-Willi syndrome?
Food seeking, MR, obesity
21
What are the symptoms of Angelman syndrome?
MR, Happy puppet
22
What is the inheritance pattern of hypophosphatemic rickets (vitamin D deficient rickets)?
X linked dominant
23
What is the inheritance pattern of MEELAS and MRRF?
Mitochondrial
24
What is the genetic defect in autosomal dominant polycystic kidney disease? (which two proteins on which two chromosomes)
Mutation in PKD1 on chromosome 16 and PKD2 on 4
25
What is the genetic cause of familial adenomatous polyposis (HNPCC)? Which chromosome is this on?
Mutation of APC gene on chromosome 5
26
What is the genetic defect in familial hypercholesterolemia?
Defective LDL receptor
27
What is hereditary hemorrhagic telangiectasia?
Inherited disorder of blood vessels
28
What is hereditary spherocytosis?
Spheroid erythrocytes due to spectrin or ankyrin defect
29
What is the genetic bases of huntington's disease?
CAG repeats on chromosome 4
30
