IVD RCAN1/SE X/SE Y

Chromosomal abnormalities involving the X and Y chromosome (sex chromosomes) are slightly less common than autosomal abnormalities and are usually much less severe in their effects. The high frequency of people with sex chromosome aberrations is partly due to the fact that they are rarely lethal conditions.
- Turner syndrome occurs when females inherit only one X chromosome - their genotype is X0.
- Metafemales or triple-X females, inherit three X chromosomes - their genotype is XXX or more rarely XXXX or XXXXX.
- Klinefelter syndrome males inherit one or more extra X chromosomes - their genotype is XXY or more rarely XXXY, XXXXY, or XY/XXY mosaic.