title: Homozygous and compound heterozygous MMP20 mutations in amelogenesis imperfecta.
abstract: In this article, we focus on hypomaturation autosomal-recessive-type amelogenesis imperfecta (type IIA2) and describe 2 new causal Matrix metalloproteinase 20 (MMP20) mutations validated in two unrelated families: a missense mutation p.T130I at the expected homozygous state, and a compound heterozygous mutation having the same mutation combined with a nucleotide deletion, leading to a premature stop codon (p.N120fz*2). We characterized the enamel structure of the latter case using scanning electron microscopy analysis and microanalysis (Energy-dispersive X-ray Spectroscopy, EDX) and confirmed the hypomaturation-type amelogenesis imperfecta as identified in the clinical diagnosis. The mineralized content was slightly decreased, with magnesium substituting for calcium in the crystal structure. The anomalies affected enamel with minimal inter-rod enamel present and apatite crystals perpendicular to the enamel prisms, suggesting a possible new role for MMP20 in enamel formation.
authors.affiliation: Research group Evolution & Développement du Squelette-EDS, UMR 7138-SAE, Université Pierre et Marie Curie, Paris, France.
authors.forename: B
authors.initials: B
authors.lastname: Gasse
authors.forename: E
authors.initials: E
authors.lastname: Karayigit
authors.forename: E
authors.initials: E
authors.lastname: Mathieu
authors.forename: S
authors.initials: S
authors.lastname: Jung
authors.forename: A
authors.initials: A
authors.lastname: Garret
authors.forename: M
authors.initials: M
authors.lastname: Huckert
authors.forename: S
authors.initials: S
authors.lastname: Morkmued
authors.forename: C
authors.initials: C
authors.lastname: Schneider
authors.forename: L
authors.initials: L
authors.lastname: Vidal
authors.forename: J
authors.initials: J
authors.lastname: Hemmerlé
authors.forename: J-Y
authors.initials: JY
authors.lastname: Sire
authors.forename: A
authors.initials: A
authors.lastname: Bloch-Zupan
mesh_terms: D000567:Amelogenesis Imperfecta / Q000201:enzymology* / Q000235:genetics; D001031:Apatites / Q000032:analysis; D001483:Base Sequence / Q000235:genetics; D002118:Calcium / Q000032:analysis; D002675:Child, Preschool; D018389:Codon, Nonsense / Q000235:genetics; D003461:Crystallography; D003596:Cytosine; D003743:Dental Enamel / Q000648:ultrastructure; D004577:Electron Probe Microanalysis; D005091:Exons / Q000235:genetics; D005260:Female; D005808:Genes, Recessive / Q000235:genetics; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008274:Magnesium / Q000032:analysis; D053519:Matrix Metalloproteinase 20 / Q000235:genetics*; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000032:analysis; D009154:Mutation / Q000235:genetics*; D020125:Mutation, Missense / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics; D013941:Thymine
chemical_list: D001031:Apatites; D018389:Codon, Nonsense; D008903:Minerals; D003596:Cytosine; C507111:MMP20 protein, human; D053519:Matrix Metalloproteinase 20; D008274:Magnesium; D013941:Thymine; D002118:Calcium
keywords: dental anomalies; enamel; gene; human; rare disease; scanning electron microscopy