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.