We previously described a large five-generation family with autosomal dominant inheritance of hereditary motor and sensory neuropathy type I, or Charcot-Marie-Tooth disease (CMT1). The genetic defect in this family was not linked to the Duffy blood group. We investigated the possibility of a disease locus on the short arm of chromosome 1 using 12 anonymous DNA markers. Two markers, D1S2 and D1S22, showed positive linkage, suggesting the existence of a CMT1 locus on 1p. D1S2 and D1S22 are clustered in the 1p31→p22 region. However, multipoint linkage analysis, including additional DNA markers from this chromosome region, excluded a possible CMT1 locus in this part of chromosome