Duchenne muscular dystrophy (DMD) is inherited as an X-linked recessive disease that behaves as a lethal trait.1 Males who inherit the mutations become disabled and die before they have children. It was elegantly stated by J. B. S. Haldane2 in 1935 that, for genetic disorders in which the mutation rate in males and females were equal, a third of the affected cases in the population in each generation would be due to new mutations. For more than a decade there has been a controversy concerning the site of the new mutations in DMD.3-10 Resolution of this controversy will have major ramifications for both genetic counseling and preventive screening.
When faced with a sporadic case of DMD, most genetic clinics assume that there is a 66% chance that the mother is a genetic carrier and a 33% chance that the affected male represents a new mutant that occurred
Roses AD. Mutants in Duchenne Muscular Dystrophy: Implications for Prevention. Arch Neurol. 1988;45(1):84–85. doi:10.1001/archneur.1988.00520250090026
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