Genes as a diagnostic tool for autism.

An in vitro diagnostic method to determine the predisposition, onset or presence of autism spectrum disorder in a person. Said method includes detecting in that person the existence of a change in an intronic segment of the genome, whose segment is located at least within the portion of chromosome 7 as set forth in the SEC. ID. No: 1 and wherein said change includes a transition from G to A at position 5579 and / or a transition from T to C at position 5731 of the SEC. ID. No. 1