Oral and maxillofacial pathology
Phenotypic diversity and revision of the nomenclature for autosomal recessive amelogenesis imperfecta

https://doi.org/10.1016/j.tripleo.2003.08.007Get rights and content

Abstract

Purpose

The purpose of this study was to characterize the phenotype in 9 families with autosomal recessive amelogenesis imperfecta (ARAI), and to propose a classification system allowing inclusion and delineation of diverse ARAI phenotypes.

Study design

Nine families with ARAI were evaluated clinically and radiographically. Exfoliated and extracted teeth were examined via light and scanning electron microscopy, with the enamel in one case evaluated by amino acid analysis.

Results

The 9 families demonstrated diverse ARAI phenotypes including localized hypoplastic, generalized thin hypoplastic, hypocalcified and hypomaturation AI types.

Conclusions

Some ARAI phenotypes observed in this study and reported in the literature cannot be classified using currently accepted ARAI nomenclature. Therefore, we propose a revised nomenclature permitting both classification of all ARAI clinical forms and inclusion of anticipated molecular-based nomenclature, such as now exists for some X-linked and autosomal dominant AI subtypes.

Section snippets

Methods

This study was approved by the Institutional Review Board, with all study participants providing informed consent prior to entry in the study. Nine families were identified as having children with clinical manifestations consistent with a diagnosis of AI. The parents in all families showed neither clinical nor radiographic evidence of AI. None of the affected children showed clinical abnormalities involving the skin, hair, fingernails, or other systems that would suggest a syndrome-associated

Results

Nine Jordanian families were ascertained through affected probands with AI. Detailed dental evaluation of the probands, their parents and siblings revealed multiple affected children in 7 of the families. None of the parents showed evidence of AI (Fig 1). There were 20 affected and 41 unaffected offspring in the 9 families. After correction for proband ascertainment bias, the ratio of affected to unaffected siblings was found to be 1:4, consistent with autosomal recessive inheritance. Parental

Discussion

The detailed characterization of ARAI in 9 families illustrates the inadequacy of current classification systems predicated on delineating AI cases based first on phenotype and then by mode of inheritance. With the identification of genetic alterations responsible for dominant forms of AI, there is increased interest in identifying those genes responsible for recessive forms of the disease. The lack of a comprehensive classification system is problematic for studies of ARAI. Molecular-based

Conclusion

Detailed phenotypic characterization of multiple families segregating for ARAI show tremendous diversity in clinical presentation of this condition. This diversity extends beyond the clinical presentation to the microscopic and biochemical alterations of affected enamel. While the classification of ARAI recognizes 4 distinct subtypes based on phenotype, only 2 are currently recognized by OMIM.5 Refined phenotype characterization will enhance future molecular studies directed at identifying the

Acknowledgements

This research was supported by the National Institute for Dental and Craniofacial Research Grant RO1 DE12879.

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