Novel mutations in GJB2 encoding connexin-26 in Japanese patients with keratitis-ichthyosis-deafness syndrome

Background Germline missense mutations in the GJB2 gene that encodes connexin-26 (Cx26) have recently been found to be the cause of the keratitis-ichthyosis-deafness (KID) syndrome. Objectives To define the GJB2 mutations in three Japanese patients with KID syndrome. Methods Genomic DNA was extracted from peripheral blood and used to amplify the GJB2 gene. Direct sequencing and endonuclease digestion were used for mutation analysis and DNA-based diagnosis. Results We identified two heterozygous mis-sense mutations (D50Y, D50N) in the GJB2 gene in three Japanese patients with KID syndrome. All mutations were located on the first extracellular domain of Cx26. Conclusions These data expand the GJB2 mutation database and show that a dominant mutation of Cx26 can cause KID syndrome in Japanese patients.