Analysis of the putative relationship between the methylenetetrahydrofolate reductase (MTHFR) C677T mutation and ARHL rendered contradictory results (Durga et al., 2006), since this allele has been correlated with hearing impairment and HHcy, and also with a reduced risk of ARHL independent from folate and Hcy levels (Uchida et al., 2011; Fusconi et al., 2012). This evidence concerns the gene MTHFR and Hearing impairment.