GRM5 and autism: Correlation of gene-specific or genome-wide epigenetic alterations with the expression of corresponding genes could identify epigenetic mechanisms of the altered functionality of more than a dozen genes related to synaptic transmission and axonal guidance (e.g. MB-COMT, HTR2A, 5-HTT, dopamine receptors, GAD1, RELN, DTNBP1, HTR1E, NOS1, PPP3CC, GRM5, PRIMA1, SHANK3) in major mental diseases, including autism (31-33, 36, 53-57).