Charcot-Marie-Tooth (CMT) disease type CMTX has been linked with mutations in GJB1, a gene on chromosome X coding for a gap junction protein, Connexin 32. We screened the GJB1 gene for mutations by SSCP analysis and sequencing of candidate regions, in five unrelated CMT affected individuals, members of families presenting a mode of transmission and clinical findings compatible with CMTX. Mutations were detected in all five patients. Three not previously reported mutations were identified: C164T, G491A and T359A. Two patients shared the same mutation (C164T) while one had a reported mutation (C43T). Restriction enzyme digestion confirmed the sequencing results, as well as the co-segregation of the mutation with the disease. The same method was used to screen 150 control X chromosomes and the variations were not detected.