Aneuploidy of Sex Chromosomes​

- Nondisjunction of sex chromosomes produces a variety of aneuploid conditions​ - Klinefelter syndrome is the result of an extra chromosome in a male, producing XXY individuals​ - About one in 1,000 males is XYY; these males do not exhibit any syndrome​ - XXX females occur with a frequency of about one in 1,000​ - They are healthy, with no unusual physical features, though they are at risk for learning disabilities​ - Monosomy X, called Turner syndrome, produces X0 females, who are sterile; it is the only known viable monosomy in humans ​