gonadal mosaicism
Presence of genetically different cell populations within reproductive organs, potentially leading to multiple affected offspring despite normal parental testing.
Full Definition
Gonadal mosaicism occurs when an individual has both normal and mutated cells within their gonadal tissue (ovaries or testes), while somatic cells remain normal. This phenomenon can result in apparently unaffected parents having multiple children with the same genetic disorder, as some gametes carry the mutation while others do not. Gonadal mosaicism explains cases where genetic testing of parental blood shows normal results, yet recurrence occurs in subsequent pregnancies. This concept is crucial in genetic counseling for accurate recurrence risk assessment.
Usage
Usage note: Always use 'gonadal' rather than 'gonosomal'; hyphenate as compound adjective.
In Context
- "Gonadal mosaicism was suspected when the couple had a second child with the same de novo mutation." — Genetic counseling documentation
- "The recurrence risk was adjusted upward due to possible gonadal mosaicism in the unaffected parent." — Risk assessment report