Updated by: Arabinda Naik
Sex chromosome aneuploidy is the term for an abnormal number of sex chromosomes. Normally, females have two X chromosomes, while males have one X and one Y. Nondisjunction can cause individuals to be born female with one X (Turner syndrome), female with three X chromosomes (Trisomy X), male with XXY (Klinefelter syndrome), or male with XYY (XYY syndrome). Rarer combinations, such as having five X chromosomes, can also occur. Sometimes, sex chromosome aneuploidy goes unnoticed in individuals, but other times it may present as a recognizable syndrome with characteristics such as intellectual disability.
Examples of Aneuploidy:
1. Normally humans have 46 chromosomes.
2. In Klinefelter's Syndrome, males have an extra copy of the X chromosome (XXY). The total number of chromosomes becomes 47, it is referred to as trisomy.
3. In Turner's syndrome, a female is born with the absence of an X chromosome (XO). Total number of chromosomes gets reduced to 45. It is referred to as monosomy.