AP2S1 and familial hypocalciuric hypercalcemia: Associated pathogenic variants involve the CASR gene on chromosome 3q 13.3–21 (loss of mutation), with more than 300 mutations described so far (60% of all familial cases), but also involving the GNA11 (guanine nucleotide-binding protein subunit alpha-11) gene, as well as the AP2S1 (adaptor protein complex 2 subunit sigma) gene, affecting 5% and 20%, respectively, of all individuals confirmed with familial hypocalciuric hypercalcemia [97,98,99].