Germline mosaicism of MPZ Gene in Dejerine-Sottas syndrome (HMSN III) associated with hereditary stomatocytosis

We report on two sisters with Dejerine-Sottas syndrome (DSS) who had a hete rozygous Gly167Arg mutation in the myelin protein zero (MPZ) gene and hered itary stomatocytosis (HSt). Genetic haplotype analysis suggested that the a llele with the MPZ gene mutation originated from maternal lineage. However, the parents, who were normal clinically and electrophysiologically, had no mutation in the MPZ gene. Therefore, the MPZ gene mutation in these sister s was due to germline mosaicism of the MPZ gene in their mother. Stomatocyt osis was detected in their mother and a sister who had no neurological symp toms, and therefore autosomal dominant HSt was suspected in this family. As stomatocytosis is very severe in our patients with DDS, we speculate that the association of DSS with stomatocytosis is coincidental but may have add itively affected erythrocyte morphology. To our knowledge, these are the fi rst familial cases of DSS with a mutation due to germline mosaicism of the MPZ gene to be reported. (C) 1999 Elsevier Science B.V. All rights reserved .