Reciprocal expression of dystrophin and utrophin in muscles of Duchenne muscular dystrophy patients, female DMD-carriers and control subjects.

We examined muscle biopsies from patients with Duchenne muscular dystrophy (DMD: 39 patients) and Becker muscular dystrophy (BMD: 11 patients), female DMD-carriers (4 patients), and control subjects (26 persons) for the expression of dystrophin and utrophin. Control subjects showed all fibers to be dystrophin-positive, while utrophin staining was negative or weak. On the other hand, muscles from DMD patients showed the inverse staining patterns: dystrophin was negative and utrophin staining strong. Thus, there was a reciprocal pattern of expression between dystrophin and utrophin. This reciprocal relationship was confirmed to some extent at the single-fiber level in female carriers of DMD showing a mosaic immunostaining of dystrophin. We consider that utrophin may have a function similar to that of dystrophin, and compensate to some extent for dystrophin deficiency in DMD.