Molecular characterization and reclassification of a 1.18 Mbp DMD duplication following positive carrier screening for Duchenne/Becker muscular dystrophy

A 2‐month‐old male patient harboring a duplication of DMD exons 1–7 classified as pathogenic by an outside institution presented with mildly elevated creatine phosphokinase (CK); molecular breakpoint analysis by our laboratory reclassified the duplication as likely benign. To date, proband continues to develop normally with decreased CK, further supporting our reclassification. Molecular characterization of DMD duplications at the breakpoint level is necessary to accurately interpret their effects on dystrophin activity and their roles in Duchenne and Becker muscular dystrophies.