Klinefelter Syndrome
The XXY condition in is caused when nondisjunction during gamete formation produces a gamete with an extra X chromosome. The XXY genotype can then be produced at fertilization in one of two ways; either the male inherits an XX from the mother and a Y from the father or an X from the mother and a XY from the father. The offspring is thus XXY with a total of 47 chromosomes.
Since they have a Y chromosome, XXY individuals are male. They are generally taller than average with unusually long limbs. They are infertile, can develop female secondary sex characteristics, and may have language and learning disabilities. However, with proper support and treatment, most XXY males can function well in society. A common name for the XXY condition in males is Klinefelter Syndrome.