Genetic variation in CACNA1D, the gene that encodes the pore-forming subunit of the L-type calcium channel CaV1.3, has been associated with increased risk for autism spectrum disorder [23, 55–58], bipolar I disorder [2, 61], epilepsy [55, 57], schizophrenia [14, 50], hyperaldosteronism [22, 48, 54–57, 64, 70], and deafness and bradycardia [5] suggesting that CaV1.3 plays an important role in a wide variety of systems. This evidence concerns the gene CACNA1D and autism spectrum disorder.