Proper regulation of FAM111A appears to be crucial, given that heterozygous mutations in FAM111A cause two rare human syndromes, Kenny-Caffey Syndrome type 2 (KCS2) and the more severe disorder, Gracile Bone Dysplasia (GCLEB)5–8, which are characterized by skeletal abnormalities, hypoparathyroidism, hypocalcemia, and low stature. Here, FAM111A is linked to osteocraniostenosis.