title: [Sequence analysis of the connexin 26 genes from a deafness family with A1555G mutation in Huaiyin].
abstract: OBJECTIVE
  To ascertain whether connexin 26 (Cx26) gene was a nuclear modifier gene in an extensive family with matrilineal nonsyndromic deafness associated with A1555G mutation in Huaiyin, China.
  
  
  METHODS
  Following PCR-restriction fragment length polymorphism (PCR-RFLP) with ApaI restriction enzyme, Cx26 genes from 26 cases, with A1555G mitochondrial mutations in this family, and 62 controls (including 2 patrilineal relatives, 10 spouse controls and 50 unrelated controls), were sequenced.
  
  
  RESULTS
  Compared with the reference sequence of Cx26 gene, totally four kinds of nucleotide changes,79G -->A, 109G-->A, 341G-->A and 235delC, were detected in a heterozygous form. However, the former three were previously reported polymorphisms, and only the 235delC was a previously described recessive mutation associated with most autosomal nonsyndromic sensorineural hearing loss in Japan and China. Further study showed that the heterozygous 235delC mutation existed in both one individual with mild hearing loss and two individuals with normal hearing. Clinical characterization showed that 235delC mutation did not seem to modify the deafness phenotype due to the A1555G mutation. Moreover, this 235delC mutation was deduced to derive from a married-in control. Finally, there were no co-segregation between the phenotypes of hearing loss and the genotypes for Cx26 genes based on the four kinds of nucleotide changes.
  
  
  CONCLUSIONS
  The heterozygous 235delC mutation of the Cx26 gene may not modulate the severity of hearing loss associated with A1555G mutation and Cx26 gene is unlikely to be a modifier gene for hearing loss due to A1555G mitochondrial mutation in this Chinese family.
authors.affiliation: Genetics Research Center, School of Medicine, Southeast University, Nanjing 210009, China.
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Zhang
authors.forename: Chun-Hong
authors.initials: CH
authors.lastname: Xu
authors.forename: Yi-Ju
authors.initials: YJ
authors.lastname: Zhang
authors.forename: Su-Ying
authors.initials: SY
authors.lastname: Zhao
authors.forename: Xue-Xia
authors.initials: XX
authors.lastname: Geng
authors.forename: Yun-Feng
authors.initials: YF
authors.lastname: Shan
authors.forename: Gang
authors.initials: G
authors.lastname: Fan
authors.forename: Guang-Qian
authors.initials: GQ
authors.lastname: Xing
authors.forename: Xiang-Nian
authors.initials: XN
authors.lastname: Shan
authors.forename: Xing-Kuan
authors.initials: XK
authors.lastname: Bu
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D003638:Deafness / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D017421:Sequence Analysis; D055815:Young Adult
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26