If a gene is found on the X chromosome (and, less commonly onthe Y chromosome), it is said to be asex-linked trait.There are about 1,098 human X-linked genes. Most of them codefor something other than female anatomical traits. Many of thenon-sex determining X-linked genes are responsible for abnormalconditions such as hemophilia, Duchenne muscular dystrophy,fragile-X syndrome, some for high blood pressure, congenital nightblindness, G6PD deficiency, and the most common human geneticdisorder, red-green color blindness.X-linked genes are also responsible for a common form ofbaldness referred to as "male pattern baldness".