title: Methylenetetrahydrofolate reductase C677T gene mutation as risk factor for sudden sensorineural hearing loss: association with plasma homocysteine, folate and cholesterol concentrations.
abstract: OBJECTIVE
  Impaired cochlear perfusion appears to be the most important event in the development of sudden sensorineural hearing loss. Methylenetetrahydrofolate reductase gene mutations at nucleotide 677 cause reduced methylenetetrahydrofolate reductase enzyme activity, resulting in vascular impairment.
  
  
  METHODS
  Thirty-three patients and 68 control subjects underwent audiological and haematological investigation.
  
  
  RESULTS
  No statistically significant association was found between sudden sensorineural hearing loss and the methylenetetrahydrofolate reductase C677T gene mutation. Mean homocysteine and cholesterol concentrations were significantly higher in patients than in controls. Mean folate levels were significantly lower in patients than in controls. Amongst patients with sudden sensorineural hearing loss, no significant differences in mean cholesterol, homocysteine or folate concentration were found, comparing patients with methylenetetrahydrofolate reductase C677T mutation genotypes with those without.
  
  
  CONCLUSIONS
  No statistically significant association was found between the methylenetetrahydrofolate reductase C677T gene mutation and sudden sensorineural hearing loss. There was a statistically significant difference between the homocysteine, folate and cholesterol concentrations of sudden sensorineural hearing loss patients, compared with controls. However, there was no statistically significant difference in these levels, comparing patients with and without the methylenetetrahydrofolate reductase C677T mutation.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonbuk National University School of Medicine, Jeon-ju, South Korea. imaima97@naver.com
authors.forename: E J
authors.initials: EJ
authors.lastname: Lee
authors.forename: Y J
authors.initials: YJ
authors.lastname: Cho
authors.forename: Y J
authors.initials: YJ
authors.lastname: Yoon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D002784:Cholesterol / Q000097:blood*; D003051:Cochlea / Q000098:blood supply; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006319:Hearing Loss, Sensorineural / Q000097:blood / Q000235:genetics*; D003639:Hearing Loss, Sudden / Q000097:blood / Q000235:genetics*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D012307:Risk Factors; D055815:Young Adult
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D002784:Cholesterol; D042965:Methylenetetrahydrofolate Reductase (NADPH2)