The influence of MTHFR heterozygous mutations (HE) showed no significant alteration in the case of healthy colorectal tissue samples (Figure 6A), while significantly lower methylation levels were detected in AD HE specimens of both mutant alleles (C677T, A1298C) compared to the wild-types (WTs) (p ≤ 0.05) (Figure 6B). This evidence concerns the gene MTHFR and Alzheimer disease.