The recurrently mutated alanine 961 in Cav3.1 [p.(Ala961Thr)], underlying severe developmental delay, cerebellar atrophy with or without epilepsy,11 is located next to the isoleucine corresponding to Ile860 in Cav3.3 which is mutated in Patient 1 and Family 2 reported here (Supplementary Fig. 1). This evidence concerns the gene CACNA1I and Global developmental delay.