Identification of an Enamelin Defect Resulting in Amelogenesis Imperfecta
Jessica Claire Massie
Purpose: The purpose of this study was to identify the genetic defect in a child, which resulted in Amelogenesis Imperfecta (AI) using saliva collected from a routine patient visit.
Methods: A 10-year old female presented to the UCSF Pediatric Dental Clinic with sensitivity and esthetic concerns. She and her 59-year old father, both indicated a history significant for AI. Saliva was collected from the proband, her affected father, and her unaffected mother using the Oragene DNA collection kit from which their DNA was manually purified. A family history was taken to identify the mode of inheritance and enamelin (ENAM) was chosen as a candidate gene. Primer sets were generated to amplify the entire ENAM gene, and amplified products were sequenced.
Results: The family pedigree revealed an autosomal dominant inheritance pattern for AI. A clinical exam revealed a mixed dentition with generalized rough, pitted, yellow-brown enamel consistent with the hypoplastic phenotype reported for AI resulting from a defect in the enamel matrix protein, enamelin. PCR amplification of genomic DNA revealed a novel mutation in exon 7, at g.10602C>G that replaces Pro with Arg, which would alter the protein structure.
Conclusion: When patients present with inherited tooth defects, the dentist's role is to describe the phenotype and obtain a family pedigree of the inheritance pattern. Additionally, collecting a patient's saliva is a simple, painless procedure, which can be used for DNA purification, mutational analysis, and diagnosis of inherited tooth defects such as AI.