Aneuploidy refers to the condition where the number of chromosomes, the diploid number, of an organism is abnormal.
Aneuploidy in human allosomes (sex chromosomes) may result in the following disorders:
XO - Turner symdrome
XXX - Metafemale
XXXX - Metafemale, with symptoms of Down symdrome
XYY - Jacob syndrome
XXY - Klinefelter syndrome
XXXY - Klinefelter syndrome, severe
Depending on the number of allosomes a person has, the aneuploidy is classified as nullisomy, monosomy, trisomy, or polysomy.