Genetic Terms Flashcards

1
Q

Codominance

A

Both alleles contribute to the phenotype of the heterozygote (ex: Blood groups AB)

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2
Q

Variable expressivity

A

People with the same genotypes have different phenotypes

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3
Q

Incomplete penetrance (calculate risk of expressing phenotype)

A

Not all individuals with disease exhibit classic phenotypes of the disease.
% penetrance x probability of inheritance = risk of expressing phenotype

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4
Q

Pleiotropy

A

One gene contributes to multiple phenotypes (PKU manifests as light skin, intellectual disability, and musty body odor)

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5
Q

Anticipation

A

Increased severity or earlier onset (more severe outcome) in next generations

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6
Q

Loss of heterozygosity

A

If a mutation is present in a tumor suppressor gene, the wild type allele must be deleted/mutated before cancer can develop. “Two-hit hypothesis”

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7
Q

Epistasis

A

The allele of one gene affects the phenotype expression in another gene

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8
Q

Aneuploidy (and due to what?)

A

An abnormal number of chromosomes due to chromosomal nondisjunction during mitosis/meiosis

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9
Q

Dominant negative mutation

A

A heterozygote produces a nonfunctional mutant protein that also prevents the wild type protein from functioning. Exerts a dominant effect.

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10
Q

Linkage disequilibrium

A

Tendency of alleles to occur in close proximity within the same chromosome more/less often than expected. Measured throughout populations

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11
Q

Mosaicism

A

Genetically different cells in the same tissues/organs

Somatic: mutation from mitotic errors
Germline: mutation from egg/sperm cells

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12
Q

Locus heterogeneity

A

Mutations at different loci resulting in the same disease

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13
Q

Allelic heterogeneity

A

Same locus, different mutations, result in the same disease

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14
Q

Heteroplasmy

A

Normal and mutated mtDNA resulting in variable expression in mitochondrial disease. To distinguish between all the other heteros remember heteroplasMy = mitochondria

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15
Q

Uniparental disomy

A

Offspring receives 2 copies of a chromosome from one parent and NONE from the other parent.

Heterodisomy (one I) = heterozygous meiosis I error
Isodisomy (two I’s) = homozygous meiosis II error or postzygotic chromosomal duplication of one pair of chromosome and complete loss of the other original pair

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