Hereditary motor and sensory neuropathy russe, a form of autosomal recessive Charcot–Marie–Tooth disease, is a rare disorder found in several Roma families from Europe. The gene has been mapped to a 1 Mb region on 10q22. Detailed analysis led to the exclusion of 22 candidate genes and the assembly of a high-density genetic map comprising 141 polymorphic markers. Extensive genotyping in an extended sample of affected families resulted in a 10-fold reduction of the critical hereditary motor and sensory neuropathy russe gene region, which is now contained within a single completely sequenced BAC clone. The fact that no sequence variant has been detected in the known genes in the critical region indicates that the hereditary motor and sensory neuropathy russe mutation affects a novel gene that remains to be identified.