POLYMERASE CHAIN-REACTION FIBER ANALYSIS AND SOMATIC MOSAICISM IN AUTOPSIED TISSUE FROM A MAN WITH DUCHENNE MUSCULAR-DYSTROPHY

Single muscle fibers, obtained at autopsy from a 22-year-old man with Duchenne muscular dystrophy were examined immunocytochemically and als o using polymerase chain reaction (PCR). Dystrophin-positive cells wer e widespread in skeletal, cardiac, smooth muscle, and in brain cells. PCR and Southern blot analyses of DNA from peripheral blood lymphocyte s revealed a deletion of exon 45 in the dystrophin gene. With PCR of s ingle fibers, three bands corresponding to exons 44, 45, and 47 were p resent in the normal control muscle fibers and dystrophin-positive fib ers from the patient, while only two bands, exons 44 and 47, were obse rved in dystrophin-negative fibers. Therefore, in this patient, the ge notype of dystrophin-positive fibers differed from that of the dystrop hin-negative fibers, possibly because of a somatic mosaicism for delet ion in the dystrophin gene. A mutation of the dystrophin gene may have occurred in one cell at an early stage of ontogenesis.