How are X-linked metabolic disorders inherited?

X-linked metabolic disorders are inherited through mutations located on the X chromosome. Because males possess only one X chromosome (paired with a Y chromosome), they lack a compensating normal gene and will be affected if they inherit the mutation.1

Transmission patterns include:
* Fathers to Sons: Fathers cannot transmit X-linked diseases to their sons because they pass only the Y chromosome to them.1
* Fathers to Daughters: Fathers can transmit the carrier state (the mutant X chromosome) to all of their daughters.1
* Mothers to Offspring: A female carrier has a 50 percent chance of passing the mutation to her children, potentially resulting in an affected son or a carrier daughter.1

Inheritance is further influenced by X chromosome inactivation, a process where one X chromosome is randomly silenced in female cells. If a higher proportion of normal X chromosomes are inactivated, a female carrier may exhibit symptoms, becoming a manifesting heterozygote. Examples of such conditions include ornithine transcarbamylase deficiency, X-linked adrenoleukodystrophy, and Lesch-Nyhan syndrome.1