The occurrence of mutations in peripheral myelin protein 22 is one of the genetic mechanisms associated with Dejerine-Sottas neuropathy (DSN). On direct sequencing 2 of such patients we have found the first mutation in the third transmembrane domain associated with this neuropathy and the fourth Ser72Leu. We propose that the Ser72 may be a "hot spot" for DSN and that this should be considered for molecular analysis.