title: Digenic inheritance of non-syndromic deafness caused by mutations at the gap junction proteins Cx26 and Cx31.
abstract: Mutations in the genes coding for connexin 26 (Cx26) and connexin 31 (Cx31) cause non-syndromic deafness. Here, we provide evidence that mutations at these two connexin genes can interact to cause hearing loss in digenic heterozygotes in humans. We have screened 108 GJB2 heterozygous Chinese patients for mutations in GJB3 by sequencing. We have excluded the possibility that mutations in exon 1 of GJB2 and the deletion of GJB6 are the second mutant allele in these Chinese heterozygous probands. Two different GJB3 mutations (N166S and A194T) occurring in compound heterozygosity with the 235delC and 299delAT of GJB2 were identified in three unrelated families (235delC/N166S, 235delC/A194T and 299delAT/A194T). Neither of these mutations in Cx31 was detected in DNA from 200 unrelated Chinese controls. Direct physical interaction of Cx26 with Cx31 is supported by data showing that Cx26 and Cx31 have overlapping expression patterns in the cochlea. In addition, by coimmunoprecipitation of mouse cochlear membrane proteins, we identified the presence of heteromeric Cx26/Cx31 connexons. Furthermore, by cotransfection of mCherry-tagged Cx26 and GFP-tagged Cx31 in human embryonic kidney (HEK)-293 cells, we demonstrated that the two connexins were able to co-assemble in vitro in the same junction plaque. Together, our data indicate that a genetic interaction between these two connexin genes can lead to hearing loss.
authors.affiliation: Department of Otolaryngology (D-48), University of Miami, 1666 NW 12th Avenue, Miami, FL 33136, USA. xliu@med.miami.edu
authors.forename: Xue-Zhong
authors.initials: XZ
authors.lastname: Liu
authors.forename: Yongyi
authors.initials: Y
authors.lastname: Yuan
authors.forename: Denise
authors.initials: D
authors.lastname: Yan
authors.forename: Emilie Hong
authors.initials: EH
authors.lastname: Ding
authors.forename: Xiao Mei
authors.initials: XM
authors.lastname: Ouyang
authors.forename: Yu
authors.initials: Y
authors.lastname: Fei
authors.forename: Wenxue
authors.initials: W
authors.lastname: Tang
authors.forename: Huijun
authors.initials: H
authors.lastname: Yuan
authors.forename: Qing
authors.initials: Q
authors.lastname: Chang
authors.forename: Li Lin
authors.initials: LL
authors.lastname: Du
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Guojian
authors.initials: G
authors.lastname: Wang
authors.forename: Shoeb
authors.initials: S
authors.lastname: Ahmad
authors.forename: Dong Yang
authors.initials: DY
authors.lastname: Kang
authors.forename: Xi
authors.initials: X
authors.lastname: Lin
authors.forename: Pu
authors.initials: P
authors.lastname: Dai
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D003051:Cochlea / Q000378:metabolism; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics* / Q000378:metabolism; D003638:Deafness / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009154:Mutation; D010375:Pedigree; D025941:Protein Interaction Mapping
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; C000607043:Gjb2 protein, mouse; D000072259:Connexin 26; C068044:GJB3 protein, human