Dystrophinopathy expressing as either cardiomyopathy or Becker dystrophy in the same family

Dystrophinopathies include different conditions caused by alterations of the Xp21 gene. The clinical spectrum encompasses the typical Duchenne phenotype: early onset muscular weakness; loss of ambulation by 12 years of age and severe progression, with death in the second or third decade; and the more slowly progressive Becker muscular dystrophy, often with a normal life span. Recently, other presentations have been described, including exercise intolerance with muscle cramps and myoglobinuria, late-onset benign muscle weakness, isolated increase of serum creatine kinase (CK), and congestive cardiomyopathy without muscle weakness.1 Although the correspondence between the phenotype and the molecular alteration is not absolute, the clinical expression of dystrophinopathies in affected members of single families carrying the same mutation is usually similar.2 A 65-year-old man (figure, A; II-2) presented to us following the incidental finding of increased serum CK in his 5-year-old grandson (figure, A; IV-2). He had a family history of “cardiomyopathy,” which caused the death of his mother (figure, A; I-1) and two brothers (figure, A; II-3, II-4) in their sixth decade. He had two healthy daughters; one …