title: Mutational hot spot in the DSPP gene causing dentinogenesis imperfecta type II.
abstract: The current system for the classification of hereditary defects of tooth dentin is based upon clinical and radiographic findings and consists of two types of dentin dysplasia (DD) and three types of dentinogenesis imperfecta (DGI). However, whether DGI type III should be considered a distinct phenotype or a variation of DGI type II is debatable. In the 30 years since the classification system was first proposed, significant advances have been made regarding the genetic etiologies of inherited dentin defects. DGI type II is recognized as an autosomal dominant disorder with almost complete penetrance and a low frequency of de novo mutations. We have identified a mutation (c.52G-->T, p.V18F) at the first nucleotide of exon 3 of the DSPP (dentin sialophosphoprotein) gene in a Korean family (de novo) and a Caucasian family. This mutation has previously been reported as causing DGI type II in a Chinese family. These findings suggest that this mutation site represents a mutational "hot spot" in the DSPP gene. The clinical and radiographic features of these two families include the classic phenotypes associated with both DGI type II and type III. Finding that a single mutation causes both phenotypic patterns strongly supports the conclusion that DGI type II and DGI type III are not separate diseases but rather the phenotypic variation of a single disease. We propose a modification of the current classification system such that the designation "hereditary opalescent dentin" or "DGI type II" should be used to describe both the DGI type II and type III phenotypes.
authors.affiliation: Department of Biological and Material Sciences, University of Michigan Dental Research Lab, 1210 Eisenhower Place, Ann Arbor, MI 48108, USA.
authors.forename: Jung-Wook
authors.initials: JW
authors.lastname: Kim
authors.forename: Jan C-C
authors.initials: JC
authors.lastname: Hu
authors.forename: Jae-Il
authors.initials: JI
authors.lastname: Lee
authors.forename: Sung-Kwon
authors.initials: SK
authors.lastname: Moon
authors.forename: Young-Jae
authors.initials: YJ
authors.lastname: Kim
authors.forename: Ki-Taeg
authors.initials: KT
authors.lastname: Jang
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Chong-Chul
authors.initials: CC
authors.lastname: Kim
authors.forename: Se-Hyun
authors.initials: SH
authors.lastname: Hahn
authors.forename: James P
authors.initials: JP
authors.lastname: Simmer
mesh_terms: D002675:Child, Preschool; D003811:Dentinogenesis Imperfecta / Q000145:classification* / Q000235:genetics*; D016326:Extracellular Matrix Proteins; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation; D010375:Pedigree; D010750:Phosphoproteins; D011498:Protein Precursors / Q000235:genetics*; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein
chemical_list: D016326:Extracellular Matrix Proteins; D010750:Phosphoproteins; D011498:Protein Precursors; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein