Fengguo Zhang1, Xiaohui Bai1, Yun Xiao1, Xue Zhang1, Guodong Zhang1, Jianfeng Li1, Lei Xu2, Haibo Wang3. 1. Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, PR China; Shandong Provincial Key Laboratory of Otology, Jinan, PR China. 2. Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, PR China; Shandong Provincial Key Laboratory of Otology, Jinan, PR China. Electronic address: sdphxl@126.com. 3. Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, PR China; Shandong Provincial Key Laboratory of Otology, Jinan, PR China. Electronic address: wang.hb7585@hotmail.com.
Abstract
OBJECTIVE: To investigate the genetic causes of hearing loss in a two generation Chinese family with enlarged vestibular aqueduct syndrome (EVAS). METHODS: Clinical and genetic evaluations were conducted in a deaf proband and her normal-hearing parents. Sanger sequencing analysis of all the 21 exons, the exon-intron boundaries and the promoter in SLC26A4 gene was performed to detect the pathogenic mutations. PCR-restricted fragment length polymorphism (PCR-RFLP) was used to further identify the mutation. Phylogenetic analysis was carried out with multiple sequence alignment using BioEdit software. Three-dimensional (3D) modeling of the human wild-type and mutant SLC26A4 (NP_000432.1) was carried out using I-TASSER (http://zhanglab.ccmb.med.umich.edu/). RESULTS: Clinical examinations showed that the proband suffered from typical features of sensorineural hearing loss with enlarged vestibular aqueduct. A novel nonsense mutation c.2118C>A (p.C706X) in exon 19 was identified in compound heterozygosity with the splice-site mutation c.919-2A>G in the proband by using Sanger sequencing. The mother was a heterozygous carrier of c.919-2A>G in intron 7, while the father was a heterozygous carrier of c.2118C>A. The mutation c.2118C>A was not found in 200 unrelated controls using Sanger sequencing. PCR-RFLP showed the PCR product of the proband was not digested at 2110 by Fau I because of the c.2118C>A mutation. 3D-structure modeling indicated that the mutation c.2118C>A resulted in a truncate Pendrin protein. Protein alignment indicated high conservation of p.C706 residue in healthy Homo, Nomascus, Pan, Macaca, Canis, Sus, Mus, Rattus, Cricetulus and Xenopus. CONCLUSIONS: This study revealed a novel heterozygous mutation c.2118C>A (p.C706X) compound with c.919-2A>G in SLC26A4 gene in a patient with EVAS.
OBJECTIVE: To investigate the genetic causes of hearing loss in a two generation Chinese family with enlarged vestibular aqueduct syndrome (EVAS). METHODS: Clinical and genetic evaluations were conducted in a deaf proband and her normal-hearing parents. Sanger sequencing analysis of all the 21 exons, the exon-intron boundaries and the promoter in SLC26A4 gene was performed to detect the pathogenic mutations. PCR-restricted fragment length polymorphism (PCR-RFLP) was used to further identify the mutation. Phylogenetic analysis was carried out with multiple sequence alignment using BioEdit software. Three-dimensional (3D) modeling of the human wild-type and mutant SLC26A4 (NP_000432.1) was carried out using I-TASSER (http://zhanglab.ccmb.med.umich.edu/). RESULTS: Clinical examinations showed that the proband suffered from typical features of sensorineural hearing loss with enlarged vestibular aqueduct. A novel nonsense mutation c.2118C>A (p.C706X) in exon 19 was identified in compound heterozygosity with the splice-site mutation c.919-2A>G in the proband by using Sanger sequencing. The mother was a heterozygous carrier of c.919-2A>G in intron 7, while the father was a heterozygous carrier of c.2118C>A. The mutation c.2118C>A was not found in 200 unrelated controls using Sanger sequencing. PCR-RFLP showed the PCR product of the proband was not digested at 2110 by Fau I because of the c.2118C>A mutation. 3D-structure modeling indicated that the mutation c.2118C>A resulted in a truncate Pendrin protein. Protein alignment indicated high conservation of p.C706 residue in healthy Homo, Nomascus, Pan, Macaca, Canis, Sus, Mus, Rattus, Cricetulus and Xenopus. CONCLUSIONS: This study revealed a novel heterozygous mutation c.2118C>A (p.C706X) compound with c.919-2A>G in SLC26A4 gene in a patient with EVAS.