ITGB3 and autism spectrum disorder: Alterations in gene dosage are important contributing factors to autism spectrum disorder (ASD), as highlighted by the high frequency of copy-number variations and mutations affecting a single allele in patients with ASD.1, 2, 3, 4, 5, 6 In particular, recent genetic screens have identified patients with ASD with rare missense and protein-truncating mutations in ITGB3, the gene encoding the extracellular matrix (ECM) receptor β3 integrin.7, 8, 9, 10 Together with previous genetic studies,11,12 these findings indicate that ITGB3 haplo-insufficiency predisposes to ASD.13