The high resistance against FD-induced hearing loss exhibited by CBA/Ca mice, as compared to the C57BL/6J strain used in our previous work (Martinez-Vega et al., 2015a), suggested putative differences in genes involved in folate metabolism. However, the small size of the mouse cochleae and the histological procedures carried out precluded an expression study on the remaining samples. Nevertheless, a search carried out into the Mouse Genome Project database showed a number of single nucleotide polymorphisms (SNPs) on several genes of folate metabolism in CBA/J mice as compared to the reference C57BL/6J strain (Keane et al., 2011). No differences in Mtr, Bhmt, Dhfr, Tyms, Mthfd1 and Mthfd2 genomic sequences were found between both strains (Table 3). In contrast, several SNPs for Bhmt2, Folr1, Folr2, Mtrr, Mthfr, Shmt1 and Shmt2 were identified. Among them, a missense mutation on Folr1 for which the functional impact remains unknown, and those on Bhmt2, a gene whose hepatic expression levels have been proposed as a dietary-dependent factor conferring protection against drug intoxication (Liu et al., 2010). In this work, Liu et al. (2010) suggested that strains with higher hepatic BHMT2 levels/activity would be adapted for a lower dependence on folate for Hcy recycling by the use of S-methylmethionine as methyl donor. Clarification on whether this postulate is valid for the auditory system would require an extensive work on genomic sequencing and evaluation of several SNPs that is out of the scope of the present article.