title: Analysis of inner ear potassium recycling genes as potential factors associated with tinnitus.
abstract: Tinnitus is defined as a perception of sound in the absence of an external acoustic stimulus. Several factors are known to influence tinnitus, e.g. hearing loss, noise exposure, age, and hypertension. As only certain individuals develop tinnitus in the presence of the above risks and in approximately 50% of cases tinnitus is not attributed to any particular cause, the question arose whether this inter-individual susceptibility to tinnitus could be explained by the influence of genetic factors.
  
  
  OBJECTIVE
  To test the hypothesis that genetic variability in genes of the potassium recycling pathway is associated with increased susceptibility to tinnitus.
  
  
  METHODS
  The study group consisted of 626 subjects exposed to occupational noise (128 with tinnitus and 498 without tinnitus). 99 single nucleotide polymorphisms were investigated in 10 genes involved in the potassium recycling pathway in the inner ear, previously selected as putative noise-induced hearing loss (NIHL) candidate genes.
  
  
  RESULTS
  Nominally significant associations were obtained for 2 variants in KCNE1 (potassium voltage-gated channel, Isk-related family, member 1) and SLC12A2 (solute carrier family 12, member 2) genes. The first gene contributed to tinnitus that developed independently of hearing loss, while the second one was associated with increased susceptibility to noise-induced hearing loss.
  
  
  CONCLUSIONS
  Present findings lend support to the notion of potassium recycling pathway genes as possible risk modifiers of tinnitus in individuals with and without hearing loss. Due to the lack of replication in other independent populations these results should be seen as suggestive.
authors.affiliation: Department of Audiology and Phoniatrics, Nofer Institute of Occupational Medicine, Łódź, Poland. mmalczyk@imp.lodz.pl
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Pawełczyk
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Rajkowska
authors.forename: Piotr
authors.initials: P
authors.lastname: Kotyło
authors.forename: Adam
authors.initials: A
authors.lastname: Dudarewicz
authors.forename: Guy
authors.initials: G
authors.lastname: Van Camp
authors.forename: Mariola
authors.initials: M
authors.lastname: Śliwińska-Kowalska
mesh_terms: D016022:Case-Control Studies; D007758:Ear, Inner / Q000378:metabolism*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006317:Hearing Loss, Noise-Induced / Q000235:genetics; D006801:Humans; D008297:Male; D020641:Polymorphism, Single Nucleotide; D011188:Potassium / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D064506:Solute Carrier Family 12, Member 2 / Q000235:genetics*; D014012:Tinnitus / Q000235:genetics*
chemical_list: C489622:KCNE1 protein, human; D024642:Potassium Channels, Voltage-Gated; C578877:SLC12A2 protein, human; D064506:Solute Carrier Family 12, Member 2; D011188:Potassium