The early forms of periodontal disease are known to be familial, but the etiologies and pathogenesis are not yet understood. Comprehensive family studies provide the most promising approach to the delineation of the cause(s) of these disorders. The forms of early onset periodontitis to be evaluated in this study include prepubertal periodontitis, localized juvenile periodontitis, generalized juvenile periodontitis, and postpubertal juvenile periodontitis. The purposes of this proposed research include: (a) to reestablish the family study of EOP at the University of Maryland Dental School; (b) to expand the family study to include ascertainment of cases and relatives through the Howard University patient population; and (c) to compare and data with the ongoing family study at the MCV/VCU School of Dentistry. Interaction with other projects in this proposal are expected to be significant in the following ways: (1) ascertainment of cases through the Caries project with common follow-up protocols to be established; (2) enhancement of faculty development for clinicians and provision of research training opportunities in the rapidly expanding area of genetics; (3) reestablishment of formal research collaborations with investigators at VCU and the University of Maryland; and (4) the use of shared space, equipment and personnel as well as the reliance on Core facilities for support of the project. Plans for this study include a systematic investigation of clinical phenotypes in patients and their relatives. The initial phase of the project will involve collection of blood samples for separation and storage for future biochemical, immunologic, and DNA studies. Assessment of possible genetic heterogeneity will be possible through the formal analysis of family data grouped by phenotypic groups, and evaluation of within and among family variability in presentation and progression of the disorders. Formal genetic analysis will include etiologic hypothesis testing and comparison of potential genetic and genetic-environmental models to account for familial distribution of the disorders. Epidemiologic variables will be included in the model testing procedures to provide comprehensive assessment of genetic/epidemiologic interactions in the determination of early onset periodontal disease(s).