Failure of two memberrs of a chromosome pair to separate (disjoin) during meiosis so that both go to one daughter cell and none to the other. This mechanism is responsible for the extra chromosome 21 in trisomy 21 (Down syndrome) and for extra and missing chromosomes causing other birth defects and many spontaneous abortions (miscarriages).
MEIOTIC NONDISJUNCTION
Meaning of MEIOTIC NONDISJUNCTION in English
English dictionary of medicine. Английский словарь медицины. 2012