Craniofacial characteristics and genotypes of amelogenesis imperfecta patients

The aims of the study were to identify craniofacial characteristics in patients with the rough hypoplastic amelogenesis imperfecta (AI) phenotype and to evaluate whether craniofacial variables are related to a mutation in either of the two genes associated with AI, enamelin (ENAM) and amelogenin (AMGX). Eight children (five males and three females) with rough hypoplastic AI phenotype, aged 6.5-15 years, from three families and their parents (three males and three females) were examined clinically, radiographically, and genetically. Seventeen variables were measured on lateral cephalometric radiographs in AI affected (n = 11) and AI unaffected (n = 3) members. Craniofacial measurements were statistically analysed using a Student's t-test. In all 14 individuals, mutation analysis of the ENAM and AMGX genes was performed by direct sequencing of the coding region. All AI affected patients had hypoplastic enamel with a rough surface and malocclusions. In the vertical plane, all AI children presented an anterior and/or posterior open bite (OB). Craniofacial analysis confirmed increased vertical relationships, with increased vertical jaw relationships and higher values for gonial angle. In two AI affected families, A and B, the same heterozygous ENAM g.8344delG mutation was confirmed, while in the third family, neither ENAM nor AMGX mutation was found. All patients with rough hypoplastic AI had a moderate to severe malocclusion with increased vertical dimensions regardless of the presence or absence of the ENAM g.8344delG mutation. As an OB requires appropriate timing of therapy, it is important to diagnose these patients as early as possible.