Association of Locus Xq26.1-27.3 with Erosive Tooth Wear Phenotypes in a Group of Adolescents.

Erosive tooth wear is a multifactorial condition of an increasing prevalence. There is a need for discovering individual genetic predisposition for the development of this condition. Considering that the chromosome X locus was previously shown to be associated with dental caries, the aim of the present study was to look for the association between this locus and erosive tooth wear when dietary habits are considered as a co-factor. Saliva samples, erosive wear experience data, and dietary information from 16- to 18-year-old dental patients (n = 705) were used. Genotyping analyses were performed, and thereafter, analyses considering diet and oral hygiene data, using logistic regression, with the assumption that erosive tooth wear is a complex gene-environment model. Genotypic analyses revealed an association between chromosome X marker rs1324156 and erosive tooth wear phenotype. Logistic regression analysis showed that, in the presence of less common allele of rs12687601 and rs1324156, erosive tooth wear more likely develops when associated with numerous dietary variables from the questionnaire. These results indicate that erosive tooth wear may be the result of gene-environment interactions.

Novel WDR72 mutation and cytoplasmic localization.

The proven candidate genes for amelogenesis imperfecta (AI) are AMELX, ENAM, MMP20, KLK4, FAM83H, and WDR72. We performed mutation analyses on seven families with hypomaturation AI. A novel WDR72 dinucleotide deletion mutation (g.57,426_57,427delAT; c.1467_ 1468delAT; p.V491fsX497) was identified in both alleles of probands from Mexico and Turkey. Haplotype analyses showed that the mutations arose independently in the two families. The disease perfectly segregated with the genotype. Only persons with both copies of the mutant allele were affected. Their hypomineralized enamel suffered attrition and orange-brown staining following eruption. Expression of WDR72 fused to green fluorescent protein showed a cytoplasmic localization exclusively and was absent from the nucleus. We conclude that WDR72 is a cytoplasmic protein that is critical for dental enamel formation.

Dentinogenesis imperfecta: a review and case report of a family over four generations.

Dentinogenesis imperfecta (DGI) is one of the most common hereditary disorders of dentin formation. It follows an autosomal dominant pattern of transmission, affecting both the formation and mineralization of dentin. Either or both primary and permanent dentition is affected by it. This paper briefly reviews the manifestations of DGI Type II (DGI1) and presents a case report of a family affected with DGI1 over four generations.

A dentin sialophosphoprotein mutation that partially disrupts a splice acceptor site causes type II dentin dysplasia.

The dentin sialophosphoprotein (DSPP) gene on chromosome 4q21.3 encodes the major noncollagenous protein in tooth dentin. DSPP mutations are the principal cause of dentin dysplasia type II, dentinogenesis imperfecta type II, and dentinogenesis imperfecta type III. We have identified a DSPP splice junction mutation (IVS2-6T>G) in a family with dentin dysplasia type II. The primary dentition is discolored brown with severe attrition. The mildly discolored permanent dentition has thistle-shaped pulp chambers, pulp stones, and eventual pulp obliteration. The mutation is in the sixth nucleotide from the end of intron 2, perfectly segregates with the disease phenotype, and is absent in 200 normal control chromosomes. An in vitro splicing assay shows that pre-mRNA splicing of the mutant allele generates wild-type mRNA and mRNA lacking exon 3 in approximately equal amounts. Skipping exon 3 might interfere with signal peptide cleavage, causing endoplasmic reticulum stress, and also reduce DSPP secretion, leading to haploinsufficiency.