A Database For The Collection Of Clinical, Laboratory, And Treatment Data From Patients With Factor X Deficiency To Define The Natural History Of The Disease And Improve Patient Management

Factor X deficiency is one of the most severe rare bleeding disorders and may lead to serious spontaneous hemorrhages, particularly in patients with severe congenital forms. Acquired FX deficiency is even rarer, most frequently associated with AL amyloidosis, and remains poorly characterized. Establishing a comprehensive patient registry is essential to improve understanding of disease epidemiology, clinical manifestations, and treatment outcomes, ultimately supporting evidence-based management strategies.

Inclusion Criteria: * Presence of the informed consent to participate in the study and provide biological samples. NB: lack of consent to the storage of biological samples is not a reason for exclusion; Males or females, of all ages, with congenital or acquired coagulation FX deficiency, diagnosed by FX:C values below the normal range; \- First-degree family members of a person diagnosed with FX deficiency of all ages; \- Willingness to participate in prospective follow-up. Exclusion Criteria: * Previous organ transplant recipient; Any psychiatric disorder, other mental disorder, or any other medical disorder that 11 impairs the subject's ability to give informed consent or to comply with the requirements of the study protocol (unless a caregiver or authorized representative is willing to provide consent/assent); \- Special patient populations, including prisoners or those who are deemed medically or cognitively unsuitable for research by their treating physician; \- Inability to obtain a blood sample due to poor or limited venous access; \- Other coagulation factor deficiencies.