Home / Patient information / Genetics and hereditary diseases / Basic concepts of genetics / Modes of genetic inheritance / X-linked recessive inheritance

What is X-linked recessive inheritance pattern?

X-linked dominant inheritance means that the altered allele is recessive, so only one allele is not sufficient for disease expression, and that the affected gene is located on the X chromsome. X-linked recessive disorders are usually more common in men, who have only one X chromosome, than in women, who have two, because if they inherit the mutated allele they develop the disease. However, women, having two X chromosomes, need both alleles to be mutated for the disease to develop. If only one allele is affected, they are carriers of the disease but do not develop it.

A woman affected by an X-linked recessive disorder will always pass the mutated allele to each of her children. Her daughters will be carry the mutated gene but not develop the disease, while her sons will always develop the disease. If a man is affected, he will pass the mutated allele to all of his daughters, who again will be carriers, but to none of his sons. There is a 50% chance that a woman who carries the altered allele transmits it to her children (regardless of their gender). If it is inherited by a boy, he will develop the associated disease, but a girl will again be only a carrier of the mutated allele.

> X-linked recessive disorders: