MTHFR and autism spectrum disorder: Shaik et al. (43) attempted to use six polymorphic loci of folate metabolism-related genes including MTHFR C677T in 138 pairs of autism spectrum disorders and control samples for artificial neural network calculation, and combined with meta-analysis of 1,361 autism spectrum disorders and 6,591 normal subjects, they finally found that C677T might be one of the important risk factors for autism.