allelic heterogeneity
Pronunciation: ah-LEE-lik het-er-oh-jeh-NEE-ih-tee
Phenomenon where different mutations in the same gene cause variable clinical presentations of a genetic condition.
Full Definition
Allelic heterogeneity refers to the existence of multiple different mutations within a single gene that can cause the same genetic condition but with varying clinical severity, onset, or symptoms. This genetic principle is crucial in reproductive genetics counseling because it explains why family members with the same condition may have different clinical presentations. For example, different mutations in the CFTR gene cause varying degrees of cystic fibrosis severity. Understanding allelic heterogeneity is essential for accurate genetic counseling regarding prognosis and inheritance patterns, particularly when interpreting genetic testing results.
Usage
Usage note: Contrast with locus heterogeneity, where different genes cause similar phenotypes.
In Context
- "Allelic heterogeneity in the CFTR gene explains the wide spectrum of cystic fibrosis presentations in affected siblings." — Genetic counseling documentation
- "The genetic counselor discussed how allelic heterogeneity affects the predictability of disease severity in their unborn child." — Patient consultation summary