Hereditary Motor and Sensory Neuropathy-Russe (HMSNR) is a rare recessive form of Charcot-Marie-Tooth disease (CMT) that has been identified in the European Gypsy (Roma) population. Clinically, HMSNR manifests with typical CMT symptoms, while no associated features have been detected. Distinct neuropathological features of HMSNR include the presence of numerous clusters of thinly myelinated fibres originating from regenerative activity. HMSNR has been previously mapped to chromosome 10q using a large Bulgarian Gypsy kindred. Subsequent identification of related chromosome 10q haplotypes in Spanish and Romanian Gypsy families suggested a founder mutation in the Gypsy population as the cause of HMSNR. This thesis describes the refined mapping of the HMSNR gene by generating a high-density physical-genetic map of the HMSNR region containing 20 microsatellite markers and 229 SNPs and insertion/deletions which allowed meticulous mapping of recombination breakpoints resulting in a reduction of the HMSNR gene region from 1 Mb to just 63.8 kb. Analysis of positional candidates by direct sequencing included 14 known genes, 7 predicted genes and 42 expressed sequence tags (ESTs) nonoverlapping with the genes. 78 putative HMSNR mutations were identified, two of which exhibit complete segregation with the HMSNR phenotype. Both are located in the so-called testis-specific part of unexpected candidate gene hexokinase 1 (HK1), in a rare alternative untranslated 5’ exon of HK1 and in the adjacent downstream intron. Expression analysis of transcripts containing the alternative exon suggests that the exon is not confined to testis but may be expressed in the nervous system. It remains to be speculated how a gene that functions in the fundamental process of energy generation might be involved in a neuropathy. Further investigations are likely to expand the knowledge about the importance of HK1 in the peripheral nervous system and may elucidate new roles of HK1