ANOS1 and Kallmann syndrome: Finally, impairments on the X chromosome play an essential role in pathogenesis of Klinefelter syndrome KS (the presence of an extra X chromosome in the male karyotype) and Kallmann KAL syndrome (mutations in the KAL1 gene on the X chromosome; KAL1 is a human gene which is located on the X chromosome at Xp22.3 and is affected in some male individuals with Kallmann syndrome).