Myalgic Becker Muscular Dystrophy Due to an Exon 15 Point Mutation: Case Series and Literature Review.

Dystrophinopathies result from mutations to the DMD gene. We report 5 boys in 3 families with heterogenous phenotypes due to a point mutation in the DMD gene: a hemizygous tyrosine-to-cysteine change in exon 15 (c.1724T>C) resulting in an amino acid substitution of leucine to proline at codon 575. This mutation has been reported before, with at least 3 prior patients presenting with similar clinical findings of myalgia, myoglobinuria, and occasional muscle cramping. The mutation on DMD c.1724T>C (p.Leu575Pro) is listed in the Clinvar database as a variant of unknown significance. Our report provides contributing evidence that this alteration should be classified as pathogenic.