aneuploidy
Pronunciation: AN-yoo-ploy-dee
Abnormal chromosome number in cells, resulting from errors in chromosome segregation during meiosis or mitosis.
Full Definition
Aneuploidy refers to the presence of an abnormal number of chromosomes in a cell or organism, deviating from the normal diploid number of 46 in humans. Common forms include monosomy (missing one chromosome) and trisomy (having an extra chromosome), such as trisomy 21 causing Down syndrome. Aneuploidy is the leading cause of pregnancy loss and birth defects, with maternal age being the primary risk factor. In reproductive genetics, aneuploidy screening is performed through various methods including karyotyping, FISH analysis, and chromosomal microarray.
Usage
Usage note: Adjective form is 'aneuploid'; contrast with 'euploid' (normal chromosome number).
In Context
- "Maternal age-related aneuploidy risk increases significantly after age 35." — Genetic counseling documentation
- "The embryo showed aneuploidy for chromosome 16, making it unsuitable for transfer." — PGT-A report