Genetically, autism-associated mutations have been found in genes encoding the key enzymes of melatonin synthesis, Aralkylamine N-acetyltransferase (AANAT), and Acetylserotonin O-methyltransferase (ASMT) (24, 25), as well as a reduced expression of the gene encoding AANAT in ASD (26). This evidence concerns the gene ASMT and autism.