Mutations in human FAM111A are associated with Kenny-Caffey Syndrome, type 2 (KCS2, OMIM #127000), in which patients exhibit increased bone density, growth retardation, macrocephaly, facial dysmorphism, hypoparathyroidism, and electrolyte imbalances, including hypocalcemia and hypomagnesemia (Isojima et al., 2014; Abraham et al., 2017) or Gracile Bone Dysplasia/Osteocraniostenosis (GCLEB/OCS, OMIM #602361), characterized by skeletal/craniofacial malformations, and perinatal lethality (Unger et al., 2013; Muller et al., 2021; Rosato et al., 2022). The gene discussed is FAM111A; the disease is familial primary hypomagnesemia.