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 mutation 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 mechanism generating the deletion may have been the formation of hairpin loop structure in a single strand of DNA followed by enzymatic degradation at unpaired regions within the loop.