Terms in Genomics
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Consanguineous: The terms inbreeding and consanguinity are used interchangeably to describe unions (marriage) between couples who share at least one common ancestor. Inbreeding in population genetic terms refers to a departure from nonrandom “mating” in which individuals “mate” with those more similar (genetically) to them than if they “mated at random” in the population. The offspring of consanguineous unions may be at increased risk to genetic disorders because of the expression of autosomal recessive gene mutations inherited from a common ancestor. The closer the biological relationship between parents, the greater is the probability that their offspring will inherit identical copies of one or more detrimental recessive genes. For example, first cousins are predicted to share 12.5% (1/8) of their genes. Thus, on an average, their progeny will be homozygous (or more precisely, autozygous) at 6.25% (1/16) of gene loci (i.e., they will receive identical gene copies from each parent at these sites in their genome).Source
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Heteroplasmy vs. Homoplasmy: A cell can have some mitochondria that have a mutation in the mtDNA and some that do not. This is termed heteroplasmy. The proportion of mutant mtDNA molecules determines both the penetrance and severity of expression of some diseases. Homoplasmy refers to a cell that has a uniform collection of mtDNA: either completely normal mtDNA or completely mutant mtDNA. A unique feature of mtDNA is that, at cell division, the mtDNA replicates and sorts randomly among mitochondria. In turn, the mitochondria sort randomly among daughter cells. Therefore, in cells where heteroplasmy is present, each daughter cell may receive different proportions of mitochondria carrying normal and mutant mtDNA. Source
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Penetrance: Penetrance measures the proportion of individuals in a population who carry a specific gene and express the related trait.Source. This post of NHS might be useful too: What are reduced penetrance and variable expressivity?