However, the pathogenesis of osteoporosis has not been fully elucidated, and is multifactorial [recurrent joint bleeding, decreased mobility or prolonged immobilization [6], nutritional deficiencies (especially vitamin D), FVIII and FIX deficiency, thrombin deficiency [7], changes in osteoblast and osteoclast activity [8]. This evidence concerns the gene F8 and osteoporosis.