A SMALL INTRAEXONIC DELETION WITHIN THE DYSTROPHIN GENE SUGGESTS A POSSIBLE MECHANISM OF MUTAGENESIS

A case of Duchenne muscular dystrophy is described with an unusual mut ation consisting of a 17-bp deletion within exon 47 of the dystrophin gene. The sequences on either side of the deletion have a high degree of intrastrand base complementarity. It is hypothesised that the mecha nism generating the deletion may have been the formation of a hairpin loop structure in a single strand of DNA followed by enzymatic degrada tion at unpaired regions within the loop.