Delayed expression of dystrophin on regenerating muscle from two siblings with Becker muscular dystrophy.

We present here a unique expression of dystrophin on biopsied muscle from 2 siblings with Becker muscular dystrophy (BMD). They had neither muscle weakness nor atrophy. Clustered dystrophin-deficient fibers were constituted to regenerating basophilic fibers (mainly type 2C fiber) based on histochemical stainings. We speculate that the developmental delay in the expression of dystrophin is a characteristic finding in regenerating fibers from asymptomatic and young BMD patients, such as the siblings in this report.