mosaicism
Pronunciation: mo-ZAY-ih-sizm
The presence of two or more genetically different cell lines within a single individual, occurring due to errors in cell division during early development.
Full Definition
Mosaicism occurs when an individual has cells with different genetic compositions, typically resulting from mitotic errors during early embryonic development. This can involve chromosomal mosaicism (different chromosome numbers in different cells) or gene mosaicism (different mutations in different cell populations). In reproductive genetics, mosaicism can affect diagnostic accuracy in prenatal testing and may influence phenotypic expression of genetic conditions, as the proportion and distribution of abnormal cells varies between individuals.
Usage
Usage note: Adjective form is 'mosaic' (e.g., 'mosaic Turner syndrome').
In Context
- "Chromosomal mosaicism was detected in 15% of the cultured amniocytes." — Cytogenetics report
- "The patient exhibited Turner syndrome mosaicism with a 45,X/46,XX pattern." — Clinical genetics consultation