RecruitingClinical trialPeriodontal Disease in Rare Renal Disorders (PERIO-RA-RE)This study aims to evaluate the burden and phenotypic spectrum of periodontal disease in patients with rare kidney disorders (such as Alport syndrome, Fabry disease, and tuberous sclerosis complex) and systemic lupus erythematosus (SLE), compared with chronic kidney disease (CKD) controls and population controls. This is a cross-sectional, case-control observational study. Participants will undergo a single structured evaluation including a full-mouth periodontal examination, a clinical questionnaire, and collection of relevant clinical and nephrological data. The primary objective is to compare the prevalence of periodontitis across study groups. Secondary objectives include characterization of periodontal disease severity, prevalence of gingivitis and xerostomia, and identification of disease-specific oral phenotypes. Exploratory analyses will assess associations between periodontal disease and clinical variables such as kidney function, proteinuria, and immunosuppressive exposure.