FAM111A and Hypocalcemia: While KCS2 shows milder phenotypes with short stature, impaired skeletal development, recurrent hypoparathyroidism and hypocalcemia which requires supplement of calcium and vitamin D (Isojima et al., 2014; Unger et al., 2013), patients with OCS are usually stillborn or die shortly after birth (Müller et al., 2021; Pemberton et al., 2020).