Of or relating to a gene situated on the X chromosome or a character (2) or trait determined by such a gene. Most X-linked disorders and conditions, including Duchenne muscular dystrophy, haemophilia, and various forms of colour-blindness, are determined by recessive genes carried by females on an X chromosome but expressed predominantly in males who have only one X chromosome, preventing complementation from occurring. A female can inherit such a gene, but its effects are normally masked by a normal dominant allele, unless the female inherits the abnormal allele from both parents. See also daltonism, hologynic, Horner's law, sex-linked. Compare Y-linked. X-linkage n.