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Flashcards in Genetic Terms and Examples Deck (15):
1

Codominance

Blood groups A, B, AB
alpha1-antitrypsin deficiency

2

Variable expressivity

NF1 (varying disease severity)
Tuberous sclerosis
Androgenetic alopecia

3

Incomplete penetrance

BRCA1 (do not always result in breast or ovarian cancer)
Tuberous sclerosis

4

Pleiotropy

PKU (one gene contributes to multiple phenotypes)

5

Anticipation

Huntington Disease

6

Loss of heterozygosity

Rb ("2-hit hypothesis")

7

Dominant negative mutation

nonfunctioning mutant prevents normal gene product from functioning

8

Linkage disequilibrium

tendency for certain alleles at 2 linked loci to occur together more or less often than expected by chance

9

Mosaicism

McCune-Albright Syndrome
Down's Syndrome

10

Locus heterogeneity

Albinism (mutations at diff loci can produce same phenotype)

11

Allelic heterogeneity

beta-thalassemia (diff mutations at same locus can produce same phenotype)

12

Heteroplasmy

MELAS (presence of both normal and mutated mtDNA resulting in variable expression in mitochondrially inherited disease)

13

Uniparental disomy

individual manifesting a recessive disorder when only one parent is a carrier; Prader-Willi Syndrome and Angelman Syndrome.
Heterodisomy (meiosis I error)
Isodisomy (meiosis II error or postzygotic chromosomal duplication of one of pair of chromosomes and loss of the original pair)

14

Imprinting

Prader-Willi Syndrome (paternal gene deleted or mutated; maternal imprinting); 25% maternal uniparental disomy
Angelman Syndrome (maternal gene deleted or mutated; paternal imprinting); 5% paternal uniparental disomy

15

Polygenic inheritance

Androgenetic alopecia
DM II