x-linked dominant inheritance x-linked dominant inheritance x-linked dominant inheritance, sometimes referred to as x-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the x chromosome. as an inheritance pattern, it is less common than the x-linked recessive type. in medicine, x-linked dominant inheritance indicates that a gene responsible for a genetic disorder is located on the x chromosome, and only one copy of the allele is sufficient to cause the disorder when inherited from a parent who has the disorder. in this case, someone who expresses an x-linked dominant allele will exhibit the disorder and be considered affected. x-linked dominant inheritance x-linked dominant traits do not necessarily affect males more than females (unlike x-linked recessive traits). the exact pattern of inheritance varies, depending on whether the father or the mother has the trait of interest. all fathers that are affected by an x-linked dominant disorder will have affected daughters but not affected sons. however, if the mother is also affected then sons will have a chance of being affected, depending on whether a dominant or recessive x chromosome is passed on. when the son is affected, the mother will always be affected. some x-linked dominant conditions are embryonic lethal in males, making them appear to only occur in females. genetics as the x chromosome is one of the sex chromosomes (the other being the y chromosome), x-linked inheritance is determined by the sex of the parent carrying a specific gene and can often seem complex. this is due to the fact that, typically, females have two copies of the x-chromosome, while males have only one copy. the difference between dominant and recessive inheritance patterns also plays a role in determining the chances of a child inheriting an x-linked disorder from their parentage. x-linked dominant disorders tend to affect females more often because thay tend to be developmentally fatal in males. this is because males have only one copy of x-chromosome while females have two copies. inheritance in x-linked dominant inheritance, when the mother alone is the carrier of a mutated, or defective gene associated with a disease or disorder; she herself will have the disorder. her children will inherit the disorder as follows: of her daughters and sons: 50% will have the disorder, 50% will be completely unaffected. children of either sex have an even chance of receiving either of their mother's two x chromosomes, one of which contains the defective gene in question. when the father alone is the carrier of a defective gene associated with a disease or disorder, he too will have the disorder. his children will inherit the disorder as follows: of his daughters: 100% will have the disorder, since all of his daughters will receive one copy of his single x chromosome. of his sons: none will have the disorder; sons do not receive an x chromosome from their father. if both parents were carriers of a defective gene associated with a disease or disorder, they would both have the disorder. their children would inherit the disorder as follows: of their daughters: 100% will have the disorder, since all of the daughters will receive a copy of their father's x chromosome. of the sons: 50% will have the disorder, 50% will be completely unaffected. sons have an equal chance of receiving either of their mother's x chromosomes. in such a case, where both parents carry and thus are affected by an x-linked dominant disorder, the chance of a daughter receiving two copies of the x chromosome with the defective gene is 50%, since daughters receive one copy of the x chromosome from both parents. were this to occur with an x-linked dominant disorder, that daughter would likely experience a more severe form. some x-linked dominant conditions such as aicardi syndrome are fatal to boys; therefore only girls with these conditions survive, or boys with klinefelter's syndrome (and hence have more than one x chromosome). a few scholars have suggested discontinuing the use of the terms dominant and recessive when referring to x-linked inheritance, stating that the highly variable penetrance of x-linked traits in females as a result of mechanisms such as skewed x-inactivation or somatic mosaicism is difficult to reconcile with standard definitions of dominance and recessiveness. list of dominant x-linked diseases vitamin d resistant rickets: x-linked hypophosphatemia rett syndrome (95% of cases are due to sporadic mutations) fragile-x syndrome most cases of alport syndrome incontinentia pigmenti giuffrè–tsukahara syndrome goltz syndrome x-linked dominant porphyria aicardi syndrome