nonpenetrance

genetics

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Last updated

July 1, 2026

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Nonpenetrance in genetics refers to a situation where an individual inherits a gene that is expected to cause a particular trait or disease, but they do not exhibit any symptoms of that condition. This occurs even though the individual can still pass the gene on to their offspring, who may then display the trait or disease.1

This phenomenon is often linked to epistatic genes, which can mask the expression of other genes. While a dominant disease-causing gene might be present, an epistatic gene can prevent its phenotypic effect, leading to nonpenetrance. This explains variability in the expression of inherited diseases like Marfan syndrome and neurofibromatosis.1

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heredity
Epistatic genes
…a condition referred to as nonpenetrance. The individual in whom such a nonpenetrant mutant gene exists will be phenotypically normal but still capable of passing the deleterious gene on to offspring, who may exhibit the full-blown disease.
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…a condition referred to as nonpenetrance. The individual in whom such a nonpenetrant mutant gene exists will be phenotypically normal but still capable of passing the deleterious gene on to offspring, who may exhibit the full-blown disease.
Read More