Linkage evidence for genetic heterogeneity among kinships with hereditary motor and sensory neuropathy, type I.

Previous reports have shown linkage of hereditary motor and sensory neuropathy, type I (HMSN I), a dominantly inherited hypertrophic neuropathy, to the locus for the Duffy blood group on the long arm of chromosome 1. Two kinships that were extensively studied and reported almost 20 years ago and used to show heterogeneity among kinships with peroneal muscular atrophy and to characterize HMSN I were investigated for linkage to various blood erythrocyte and lymphocyte (HLA) antigens. Strong evidence against linkage to the Duffy blood group locus was found for one kinship, whereas suggestive evidence for linkage was found for the other. These data imply that HMSN I is heterogeneous--that is, caused by different genetic mechanisms. The HMSN I that is not linked to the Duffy locus might be identified as HMSN IA, and the HMSN I that is linked to the Duffy locus might be designated as HMSN IB. HMSN IA was not linked to other blood types or HLA antigens. In addition, no evidence for linkage to blood types and HLA was found for spastic paraplegia with peroneal muscular atrophy and sensory loss (HMSN V).