Raine syndrome: an overview.

Raine syndrome (RS) is a bone dysplasia characterised by generalised osteosclerosis with periosteal bone formation, characteristic face, and brain abnormalities [MIM # 259775]. Its prevalence is estimated to be < 1/1,000,000. Although it was originally thought always to be lethal, there have now been six reports of patients surviving into childhood and this phenotype is still being defined. The skeletal dysplasia predominantly affects craniofacial development explaining the severe proptosis, underdeveloped midface, depressed nasal bridge and short nose. The main radiological manifestation is a diffuse, marked osteosclerosis of the base of skull and long bones. Raine syndrome is caused by biallelic mutations in FAM20C, located on chromosome 7p22.3. This gene encodes a Golgi casein kinase, which phosphorylates serine residues of extracellular proteins involved in biomineralisation. Facial appearance and radiological findings allow the clinical diagnosis, and molecular testing of FAM20C can confirm this. Desmosterolosis and congenital cytomegalovirus infection may resemble Raine syndrome. If Raine syndrome is suspected prenatally the newborn should be admitted at a neonatal intensive care unit as significant respiratory distress is often present immediately after birth. We present here a review of the pertinent literature in clinical manifestations, molecular background, diagnosis and management.