Mutations in GJB2, GJB6, and mitochondrial DNA are rare in African American and Caribbean Hispanic individuals with hearing impairment

Joy Samanich, Christina Lowes, Robert Burk, Sara Shanske, J. Lu, Alan Shanske, Bernice E. Morrow

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

Autosomal recessive nonsyndromic sensorineural hearing impairment (ARNSHI) comprises 80% of familial hearing loss cases. Approximately half result from mutations in the connexin 26 (Cx26) gene, GJB2, in Caucasian populations. Heterozygous mutations in GJB2 occasionally co-occur with a deletion of part of GJB6 (connexin 30; Cx30). It is estimated that approximately 1% of deafness is maternally inherited, due to mutations in mitochondrial DNA (mtDNA). Few studies have focused on the frequency of mutations in connexins or mtDNA in African American (AA) and Caribbean Hispanic (CH) admixture populations. In this study, we performed bidirectional sequencing of the GJB2 gene and polymerase chain reaction (PCR) screening for the common GJB6 deletion, as well as PCR/RFLP analysis for three mutations in mtDNA (A1555G, A3243G, A7445G), in 109 predominantly simplex AA and CH individuals. Variations found were a 101T > C (M34T; 1/101 cases), 109G > A (V37I; 1/101), 35delG (mutation; 4/101, 3/4 of non-AA/CH ethnicity), 167delT (mutation; 1/101), 139G > T (mutation; E47X; 1/101 homozygote, consanguineous), -15C > T (1/101), 79G > A (V27I; 9/101), 380G > A (R127H; 4/101; Guyana, India, Pakistan ethnicity), 670A > C (Indeterminate; K224Q; 1/101), 503A > G (novel; K168R; 3/101) and 684C > A (novel; 1/101). All but one of the AA and CH patients had monoallelic variations. There were no hemizygous GJB6 deletions in those with monoallelic GJB2 variations. We also did not identify any patients with the three mutations in mtDNA. Bidirectional sequencing of the GJB2 gene was performed in 187 AA and Hispanic healthy individuals. Our results reveal that GJB2 mutations, GJB6 deletions, and mtDNA mutations may not be significant in these minority admixture populations.

Original languageEnglish (US)
Pages (from-to)830-838
Number of pages9
JournalAmerican Journal of Medical Genetics, Part A
Volume143
Issue number8
DOIs
StatePublished - Apr 15 2007

Keywords

  • Admixture populations
  • African American
  • Connexin 26
  • Connexin 30
  • Deafness
  • GJB2
  • GJB6
  • Gene frequency
  • Genetics
  • Hearing loss
  • Hispanic
  • Mitochondrial mutations
  • Mutation

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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