Why are sex-linked disorders more common in men?
1 Answer
Sex linked disorders are more common in men because the X chromosome contains more coding genes than the Y chromosome.
Explanation:
Women have two X chromosomes, one from each parent, although only one of these X chromosomes is active in each cell. The other one shrivels up and becomes a small, inactive fleck of DNA called a Barr body.
When one of the woman's two X chromosomes contains a loss-of-function mutation, roughly half the cells in their body will still have the healthy normal wild type X chromosome functional. Which is usually enough to produce a wild type phenotype, or an incompletely penentrant state which is still more viable than a full loss of function phenotype.
Whereas men have only one X chromosome in all their cells. If it contains a loss-of-function mutation, that gene's function is simply lost in all their cells. Which is more likely to result in serious illness or death.
