Data Collection on Rare Coagulation Disorders: Focus on Patients with Coagulation Factor X Deficiency

BACKGROUND: Inherited coagulation factor X (FX) deficiency is an ultra-rare coagulation disorder (estimated prevalence ∼1:1,000,000), characterized by reduced FX activity (FX:C) and bleeding manifestations, ranging from mild to life-threatening hemorrhage. Due to its rarity, management is currently guided by case reports and expert opinion rather than evidence-based guidelines. OBJECTIVES: The Prospective Rare Bleeding Disorders Database on Coagulation Factor X Deficiency (PRO-RBDD-FX) aims to quantify bleeding rates, identify FX:C thresholds protective against major spontaneous bleeding and evaluate treatment efficacy and safety. A secondary objective is to assess the health-related quality of life (HrQoL). METHODS: PRO-RBDD-FX is an observational study utilizing a web-based platform for the collection of retrospective and prospective longitudinal data. The registry enrolls affected probands and their first-degree relatives. Standardized demographic, clinical, laboratory, genetic, and treatment-related data are collected through dedicated modules covering bleeding manifestations, surgery, prophylaxis, thrombosis, laboratory phenotype assessment, genetics, and HrQoL. Bleeding severity is quantified using the ISTH-BAT and the EN-RBD-BSS, while HrQoL is assessed through EuroQoL questionnaires. RESULTS: The PRO-RBDD-FX project resulted in the development of a web-based registry dedicated to FX deficiency. The platform integrates clinical, laboratory, genetic, therapeutic, and patient-reported outcome data within a unified longitudinal follow-up. CONCLUSIONS: The disease-specific modules developed herein support future natural history and genotype-phenotype studies. The PRO-RBDD-FX registry represents a tool for advancing research in ultra-rare diseases, bridging the gap between laboratory findings and clinical reality promoting standardized personalized care.