The FAM20 proteins are a family of secreted proteins that regulate differentiation and function of hematopoietic and other tissues. FAM20C, also known as DMP4 (Dentin matrix protein 4), is a 570 amino acid secreted protein that binds calcium and may play a role in dentin mineralization. Defects in the gene encoding FAM20C are the cause of Raine syndrome (Lethal osteosclerotic bone dysplasia), an autosomal recessive osteosclerotic bone dysplasia, that is characterized by generalized osteosclerosis, microencephaly and craniofacial dysplasia. Usually, affected individuals survive only days or weeks. The mutations of the FAM20C gene include four nonsynomous base changes and four splice-site changes that have a detrimental affect on splicing.