Non-clinical sciences/Genetics · Inheritance

X-linked recessive

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What it means

Mutant gene on the X; affected males, carrier females; no male-to-male transmission; daughters of an affected man are obligate carriers. Examples: Duchenne/Becker muscular dystrophy, haemophilia A/B, G6PD deficiency, red–green colour blindness, Lesch-Nyhan, Bruton's, Fabry.

Worked example

Affected boys related through unaffected carrier mothers, with no father-to-son transmission → X-linked recessive.

In the exam

A condition affects boys in several generations, always inherited through unaffected mothers, and is never passed from father to son.

What settles it

X-linked recessive: no male-to-male transmission, carrier females; AR affects both sexes equally with horizontal sib clustering.

Classically confused with

Autosomal recessive

Source: StatPearls