CACNA1C and attention deficit-hyperactivity disorder: No significant effect was observed when using gene variants from CACNB1, CACNA2D3, CA1, or SMPD1. Interestingly, significant effects on ADHD were genetically predicted by variants in the genes encoding for the three tested subunits of L-type calcium channels (subunits α1-C CACNA1C; β1, CACNB1; α2δ3, CACNA2D3) and by all amlodipine target genes combined (Fig. 4D, Supplementary Table 4).