Subsequently, Simpson et al. reported that the loss-of-function mutations in the FAM20C gene were associated with lethal/non-lethal osteosclerotic bone dysplasia (Raine Syndrome) [6], [8], an autosomal recessive disorder characterized by a generalized increase in the density of all bones; these data indicated that FAM20C might be a down-regulator of biomineralization, which apparently contradicts the mineralization-promoting properties of FAM20C observed by Hao et al. This evidence concerns the gene FAM20C and lethal osteosclerotic bone dysplasia.