aneuploidy
Pronunciation: AN-you-ploy-dee
Chromosomal abnormality involving an incorrect number of chromosomes in embryos or gametes.
Full Definition
A condition where cells contain an abnormal number of chromosomes, either more or fewer than the typical diploid number of 46. In reproductive medicine, aneuploidy is a major cause of implantation failure, miscarriage, and congenital abnormalities. The incidence increases significantly with maternal age, particularly after age 35. Common examples include Down syndrome (trisomy 21) and Turner syndrome (monosomy X). Preimplantation genetic testing can screen embryos for aneuploidy before transfer to improve pregnancy outcomes.
Usage
Usage note: Distinguish from 'euploidy' (normal chromosome number) and 'polyploidy' (multiple complete chromosome sets).
In Context
- "PGT-A revealed aneuploidy in 60% of the tested embryos from the 42-year-old patient." — genetic testing report
- "Advanced maternal age significantly increases the risk of embryonic aneuploidy." — counseling documentation