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What are X-Linked recessive diseases?

Sanjay Krishnan
Sanjay Krishnan on behalf of MDLIVE
Healthcare Specialist

Human beings in general, have 2 sets of sex chromosomes, 1 set from each parent. Women have 2 sets of chromosomes called X chromosomes, one from each parent. Men have an X chromosome from their mothers, and a Y chromosome from their fathers. Therefore, an X-linked disease refers to a gene that carries a disease on the X chromosome.

In an X-Linked recessive disease, a man can get a disease if he inherits from his mother a diseased gene, although she herself might not have the disease since she has 2 X-chromosomes, one being healthy. In women, to inherit an X-Linked recessive disease, they would have to obtain a gene for the disease from both their mother and their father to have the disease. Therefore in X-Linked recessive diseases, men are generally the ones in the family who show symptoms of the disease if they inherit a disease copy of the gene from their mother, who generally is a carrier of the disease.

Dr. Jeanne Morrison, PhD
Family Practitioner

X-linked recessive conditions are carried on the X chromosome and are expressed phenotypically when there is no second X chromosome with a nonaffected allele. Thus, they are transmitted from carrier mothers to affected sons. In these conditions, each female carrier has a 50% chance of transmitting the condition to a male offspring and essentially a 0% chance of transmitting the condition to a female offspring. Each female offspring, however, has a 50% chance of being a carrier like her mother. Hemophilia is an example of an X-linked recessive condition.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.