title: Audioprofiles and antioxidant enzyme genotypes in presbycusis.
abstract: OBJECTIVE
  Audiometric patterns have been shown to indirectly provide information regarding the pathophysiology of presbycusis and be useful in the phenotyping of hereditary deafness.
  
  
  METHODS
  Hospital-based cohort study of adults with presbycusis, comparing the association of audiometric patterns and polymorphisms of antioxidant enzymes that have been linked to presbycusis: GSTT1, GSTM1 and NAT2. All subjects underwent a clinical evaluation and completed questionnaires regarding ototoxicity and noise exposure. Pure-tone threshold audiometry was obtained and subjects' audiograms were classified into specific patterns. DNA was extracted from blood and the polymorphisms of GSTT1, GSTM1, and the NAT2 variants (NAT2* 5A; NAT2* 6A,B) were analyzed by PCR.
  
  
  RESULTS
  The audiometric patterns that were more prevalent in our cohort were "High-Frequency Steeply Sloping" or HFSS (33%), "High-Frequency Gently Sloping" or HFGS (31%), and "Flat" (27%), with other patterns being rare. We did not find a statistical significant effect of gender, age, hearing level, and ear side on the audiometric pattern. Subjects with mutant alleles for GSTT1 were more likely to have a HFSS audiogram than subjects with the wild type genotype.
  
  
  CONCLUSIONS
  In this cohort, there was a similar prevalence for the three audiometric configurations HFSS, HFGS, and Flat, with other configurations being rare. Subjects with mutant alleles for GSTT1 were more likely to have a HFSS audiogram than subjects with the wild type genotype, suggesting that the basal turn of the cochlea is susceptible to GSTT1 regulated oxidative stress. However, further studies of audioprofiles with larger sample sizes may be needed to establish phenotype-genotype correlations in presbycusis.
authors.affiliation: Department of Otolaryngology, University of Miami, Miller School of Medicine, Miami, Florida 33136, USA. sangeli@med.miami.edu
authors.forename: Simon I
authors.initials: SI
authors.lastname: Angeli
authors.forename: Anthony
authors.initials: A
authors.lastname: Bared
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Ouyang
authors.forename: Li Lin
authors.initials: LL
authors.lastname: Du
authors.forename: Denise
authors.initials: D
authors.lastname: Yan
authors.forename: Xue
authors.initials: X
authors.lastname: Zhong Liu
mesh_terms: D000483:Alleles; D000975:Antioxidants; D001191:Arylamine N-Acetyltransferase / Q000235:genetics; D001299:Audiometry; D005260:Female; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011304:Presbycusis / Q000201:enzymology* / Q000453:epidemiology / Q000235:genetics*; D015995:Prevalence; D011795:Surveys and Questionnaires
chemical_list: D000975:Antioxidants; D001191:Arylamine N-Acetyltransferase; D005982:Glutathione Transferase; C478900:NAT2 protein, human; C413545:glutathione S-transferase T1