Sex chromosomal nondisjunction in diploid organisms with the XX, XY system of sex determination. In the homogametic sex, gametes are produced with two X chromosomes or none. In the heterogametic sex, primary nondisjunction during the first meiotic division produces gametes with no sex chromosome (O) or with an X and a Y. Primary nondisjunction during the second meiotic division produces XX and O or YY and O gametes.
Subjects: Genetics and Genomics.