Allen Roses, MD, draws attention to the considerable clinical importance of defining the relative mutation rates of Duchenne muscular dystrophy (DMD) in male and female gametes. The practical significance of this information is best appreciated by considering an extreme case: if all mutations occur in males, then all mothers of affected boys must be carriers (since no mutations can occur during their own oogenesis), and are therefore at high risk of having further affected sons. But if male and female mutation rates are equal, a third of mothers will be noncarriers, with a very low risk of having another affected child. There are also important strategic implications for disease prevention—carrier screening will be more effective if most affected boys are born to carrier mothers, who could, in principle, be detected before pregnancy.
Were there a reliable carrier test for DMD, this question would be resolved simply by testing mothers. In
Bobrow M, Walker A, Walton J. The Parental Origin of Mutations Causing Duchenne Muscular Dystrophy. Arch Neurol. 1988;45(1):85–87. doi:10.1001/archneur.1988.00520250091027
Monkeypox Resource Center
Customize your JAMA Network experience by selecting one or more topics from the list below.