nondisjunction

noun

1. The failure of chromosome dyads or tetrads to separate properly during meiosis or mitosis.

   “Different exogenous agents may interfere with the normal disjunction of sister chromosomes during meiosis and increase the frequency of aneuploid sperm, as demonstrated in mice treated with aneugens and men treated with anticancer agents. Although not all germ cells achieve maturity, the close correlation of chromosome nondisjunction in spermatogenesis with genotoxic outcomes indicates that the investigation for aneuploidy in a large sample of aneugen-exposed workers is significant.”