title: A missense mutation in ITGB6 causes pitted hypomineralized amelogenesis imperfecta.
abstract: We identified a family in which pitted hypomineralized amelogenesis imperfecta (AI) with premature enamel failure segregated in an autosomal recessive fashion. Whole-exome sequencing revealed a missense mutation (c.586C>A, p.P196T) in the I-domain of integrin-β6 (ITGB6), which is consistently predicted to be pathogenic by all available programmes and is the only variant that segregates with the disease phenotype. Furthermore, a recent study revealed that mice lacking a functional allele of Itgb6 display a hypomaturation AI phenotype. Phenotypic characterization of affected human teeth in this study showed areas of abnormal prismatic organization, areas of low mineral density and severe abnormal surface pitting in the tooth's coronal portion. We suggest that the pathogenesis of this form of AI may be due to ineffective ligand binding of ITGB6 resulting in either compromised cell-matrix interaction or compromised ITGB6 activation of transforming growth factor-β (TGF-β) impacting indirectly on ameloblast-ameloblast interactions and proteolytic processing of extracellular matrix proteins via MMP20. This study adds to the list of genes mutated in AI and further highlights the importance of cell-matrix interactions during enamel formation.
authors: Leeds Institutes of Molecular Medicine, University of Leeds, Leeds LS9 7TF, UK.
authors: James A
authors: JA
authors: Poulter
authors: Steven J
authors: SJ
authors: Brookes
authors: Roger C
authors: RC
authors: Shore
authors: Claire E L
authors: CE
authors: Smith
authors: Layal
authors: L
authors: Abi Farraj
authors: Jennifer
authors: J
authors: Kirkham
authors: Chris F
authors: CF
authors: Inglehearn
authors: Alan J
authors: AJ
authors: Mighell
mesh_terms: D000567:Amelogenesis Imperfecta / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000235:genetics; D003743:Dental Enamel / Q000378:metabolism / Q000473:pathology; D059472:Exome / Q000235:genetics; D005808:Genes, Recessive; D006801:Humans; D007124:Immunoenzyme Techniques; D039641:Integrin beta Chains / Q000502:physiology*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D055114:X-Ray Microtomography
chemical_list: D039641:Integrin beta Chains; C072170:integrin beta6; D004247:DNA