GNA11 and familial hypocalciuric hypercalcemia: To further elucidate the role and spectrum of AP2σ2 mutations in the aetiology of the phenotypic features of FHH3, we conducted studies to characterise the structural/functional consequences of AP2σ2 mutations together with their underlying genetic mechanisms in additional FHH patients, who did not have CASR or GNA11 mutations.