title: Non-syndromic hearing impairment in a multi-ethnic population of Northeastern Brazil.
abstract: OBJECTIVE
  There are many hearing impaired individuals in Monte Santo, a rural municipality in the state of Bahia, Brazil, including multiple familial cases strongly suggestive of a genetic aetiology.
  
  
  METHODS
  The present study investigated 81 subjects with hearing impairment (HI) recruited from 36 families. Mutations often associated with HI, i.e. the DFNB1 mutations c.35delG in GJB2, deletions del(GJB6-D13S1830) and del(GJB6-D13S1854), and A1555G in the mitochondrial gene MTRNR1 were initially analyzed, with additional mutations in GJB2 identified by sequencing the coding region of the gene.
  
  
  RESULTS
  Seven different mutations were present in GJB2 with mutations c.35delG and p.Arg75Gln, which are known to be pathogenic, identified in 37.0% of the subjects. Individuals homozygous for the c.35delG mutation were diagnosed in eight families, corresponding to 24.7% of unrelated individuals with nonsyndromic hearing impairment (NSHI), and an additional heterozygote for this mutation was present in a single family. Ten individuals (12.4%) in another family were heterozygous for the mutation p.Arg75Gln.
  
  
  CONCLUSIONS
  Significant heterogeneity was observed in the alleles and patterns of NSHI inheritance among the subjects studied, probably due to the extensive inter-ethnic admixture that characterizes the peoples of Brazil, together with a high prevalence of community endogamy and consanguineous marriage.
authors.affiliation: Advanced Laboratory of Public Health/Gonçalo Moniz Research Center (CPqGM), Oswaldo Cruz Foundation (FIOCRUZ), Salvador, Bahia, Brazil.
authors.forename: Gabrielle N
authors.initials: GN
authors.lastname: Manzoli
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Abe-Sandes
authors.forename: Alan H
authors.initials: AH
authors.lastname: Bittles
authors.forename: Danniel S D
authors.initials: DS
authors.lastname: da Silva
authors.forename: Luciene da C
authors.initials: Lda C
authors.lastname: Fernandes
authors.forename: Roberta M C
authors.initials: RM
authors.lastname: Paulon
authors.forename: Iza Cristina S
authors.initials: IC
authors.lastname: de Castro
authors.forename: Carla M C A
authors.initials: CM
authors.lastname: Padovani
authors.forename: Angelina X
authors.initials: AX
authors.lastname: Acosta
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D003241:Consanguinity; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D034381:Hearing Loss / Q000208:ethnology* / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D057093:Orphan Nuclear Receptors / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012424:Rural Population / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; C403073:NR2E3 protein, human; D057093:Orphan Nuclear Receptors; D000072259:Connexin 26