X-linked dominant inheritance

In this case, someone who expresses an X-linked dominant allele will exhibit the disorder and be considered affected.

The exact pattern of inheritance varies, depending on whether the father or the mother has the trait of interest.

Some X-linked dominant conditions are embryonic lethal in males, making them appear to only occur in females.

Their children would inherit the disorder as follows: 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.

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.