FAM20C and lethal osteosclerotic bone dysplasia: FAM20C is a kinase that phosphorylates many extracellular matrix proteins involved in biomineralization and other biological processes.2, 3FAM20C is ubiquitously expressed,1, 4, 5 and mutations in the human FAM20C gene cause Raine syndrome, an autosomal recessive disorder that demonstrates a broad spectrum of clinical manifestations.6, 7, 8, 9, 10Fam20C-deficient mice developed hypophosphataemic rickets, along with severe dental defects.11, 12