We therefore decided to study the genetic variability of the melatonin receptor MTNR1A and MTNR1B genes and the GPR50 gene in autism spectrum disorder (ASD) patients, in parallel to a normal European control population as well as in individuals of the human genome pluriethnic diversity panel (HGDP), by direct sequencing of the coding regions. This evidence concerns the gene MTNR1B and autism spectrum disorder.