Suggested clarification:
The current wording states that “X-linked recessive diseases are more severe in males,” but this phrasing is imprecise. A more accurate statement would be that X-linked recessive diseases are more frequently expressed in males.
Explanation:
Males are hemizygous for the X chromosome, so a single mutant allele will result in full disease expression. Most females, however, are heterozygous carriers, and due to random X-inactivation, they typically have milder or no symptoms. This creates the appearance of greater severity in males.
However, a homozygous female with two mutant alleles would express the disease as fully as an affected male, and may be equally or more severely affected. These cases are simply much less common. Thus, the primary difference is in frequency of full disease expression, not an inherent difference in biological severity between sexes.
No source provided. Also, the more frequent expression is discussed in the table
