title: Novel TMC1 structural and splice variants associated with congenital nonsyndromic deafness in a Sudanese pedigree.
abstract: Mutations of the transmembrane channel-like gene 1 (TMC1) have been shown to cause autosomal dominant and recessive forms of congenital nonsyndromic deafness linked to the loci DFNA36 and DFNB7/B11, respectively. In a Sudanese pedigree affected by an apparently recessive form of nonsyndromic deafness, we performed a linkage analysis using markers covering the deafness loci DFNB1 - DFNB30. A two-point LOD score of 3.08 was obtained at marker position D9S1876, located within the first intron of the TMC1 gene at DFNB7/B11. By DNA sequencing of TMC1 exons 3-22, we identified the structural variant c.1165C>T in exon 13, leading to the stop codon p.Arg389X, and the splice-site variant c.19+5G>A, independently segregating with the deafness phenotype. The c.1165C>T [p.Arg389X] mutation was also observed in four out of 243 unrelated deaf Sudanese individuals, but none of the mutations was found among 292 normal hearing controls. The finding of TMC1 mutations contributing to deafness in Sudan confirms and extends previous reports on the role of TMC1 in recessive nonsyndromic deafness and shows that deafness-causing TMC1 mutations may occur in various ethnic groups.
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany. c.g.meyer@bni.uni-hamburg.de
authors.forename: Christian G
authors.initials: CG
authors.lastname: Meyer
authors.forename: Nagla M
authors.initials: NM
authors.lastname: Gasmelseed
authors.forename: Adil
authors.initials: A
authors.lastname: Mergani
authors.forename: Mubarak M A
authors.initials: MM
authors.lastname: Magzoub
authors.forename: Birgit
authors.initials: B
authors.lastname: Muntau
authors.forename: Thorsten
authors.initials: T
authors.lastname: Thye
authors.forename: Rolf D
authors.initials: RD
authors.lastname: Horstmann
mesh_terms: D002899:Chromosomes, Human, Pair 9; D000072259:Connexin 26; D017630:Connexins; D003241:Consanguinity; D004252:DNA Mutational Analysis; D003638:Deafness / Q000151:congenital / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D009154:Mutation; D010375:Pedigree; D012326:RNA Splicing / Q000235:genetics; D013397:Sudan
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D008565:Membrane Proteins; C451751:TMC1 protein, human; D000072259:Connexin 26