We hypothesized that exome sequencing analysis and comparative genetic evaluation of reported cases with 12p13.33–p13.32 microdeletion would provide sufficient data to confirm that CACNA1C and KDM5A genes of the six candidate genes located in this region were the best candidates for explaining epilepsy, ID, and schizophrenia and may be responsible for clinical features reported in cases with monosomy of the 12p13.33 subtelomeric region. Here, CACNA1C is linked to epilepsy.