Odds ratios ranging from 1.16 to 1.74 were observed in this study, and P values supported a nominal association for individual variants of EN2, ATP2B2 and PITX1, but not SLC25A12. However, because of its reported genetic association with autism [26,27,29] and the possible relationship with autism of its overexpression [48], it was included in the combined analysis. Here, PITX1 is linked to autism.