Association of folate with hearing is dependent on the 5,10-methylenetetrahdyrofolate reductase 677C → T mutation

• Published in: Neurobiology of aging Vol. 27; no. 3; pp. 482 - 489
• Main Authors: Durga, Jane, Anteunis, Lucien J.C., Schouten, Evert G., Bots, Michiel L., Kok, Frans J., Verhoef, Petra
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2006
• Subjects: 5,10-Methylenetetrahydrofolate reductase; 5,10-Methylenetetrahydrofolate Reductase (FADH2) - blood; 5,10-Methylenetetrahydrofolate Reductase (FADH2) - genetics; Age-related hearing loss; Aged; Auditory Threshold; Female; Folate; Folic Acid - blood; Genetic Predisposition to Disease; Hearing Loss, Sensorineural - blood; Hearing Loss, Sensorineural - diagnosis; Hearing Loss, Sensorineural - epidemiology; Hearing Loss, Sensorineural - genetics; Homocysteine; Homocysteine - blood; Humans; Incidence; Male; Middle Aged; Mutation; Netherlands - epidemiology; Polymorphism, Genetic; Risk Assessment - methods; Risk Factors; Severity of Illness Index; Vascular disease; Vitamin B 12; Vitamin B 12 - blood; Vitamin B 6; Netherlands; Vascular disease; Vitamin B 6; 5,10-Methylenetetrahydrofolate reductase; Age-related hearing loss; Vitamin B 12; Homocysteine; Folate
• ISSN: 0197-4580; 1558-1497
• DOI: 10.1016/j.neurobiolaging.2005.03.002

Vascular disease and its risk factors have been associated with the age-related hearing loss. We examined the association of elevated plasma homocysteine and its determinants with hearing levels. Pure-tone air conduction thresholds in 728 individuals with sensorineural hearing loss were not associated with homocysteine, erythrocyte folate and Vitamin B 6. Low concentrations of serum folate and Vitamin B 12 were associated with better hearing. When folate status was below the median, 5,10-methylenetetrahydrofolate reductase (MTHFR) 677TT homozygotes had similar hearing levels to subjects with a C allele. However, when folate status was above the median, MTHFR 677TT homozygotes had on an average 5 dB ( p = 0.037) and 2.6 dB ( p = 0.021) lower PTA-high and PTA-low hearing thresholds, respectively, than the subjects with a 677C allele. The relationship between serum folate and hearing thresholds appeared to be dependent on MTHFR 677 genotype (CC, r = 0.13, p = 0.034; TT, r = –0.10, p = 0.291). This supports the hypothesis that a greater one-carbon moiety commitment to de novo synthesis of nucleotides and an increase in formyl-folate derivatives relative to methyl-folate derivatives is protective for hearing.