MTR and autism: Finally, significantly lower methionine synthase mRNA along with lower levels of homocysteine and cystathionine were observed in the frontal cortex (BA 9, 22, 41, 42, or 46) in the brains of 10 individuals with autism (ages 4–30 years) compared to 10 age- and sex-matched controls, suggestive of adaptive responses to oxidative stress (Muratore et al., 2013).