Osteopetroza

Osteopetroza known as "marble bone disease is a clinical syndrome characterized by failure to resolve bone osteoclasts. As a result, affected bone remodeling and modeling. The defect in bone turnover result in bone fragility despite high bone mass and may lead to hematopoietic failure, abnormal tooth eruption, and impaired nerve syndromes incarceration growth.Osteopetroza human disease is a heterogeneous comprising different molecular lesions and a variety of clinical features.Untreated osteopetroza cause infant death within the first decade of life, severe anemia, bleeding and infection. Osteopetroza adults are usually asymptomatic and have good survival rate.
Osteopetroza infantile or malignant osteopetroza is diagnosed early in life. Clinical manifestations include: staturo-weight retardation, bone defects, deafness, nerve neuropathy by incarceration, hidrocefalus, delayed dentition, mandibular osteomyelitis. Bones are fragile and fractures easily. Paranasal sinuses and clogging mastoidiene by birth. Osteopetroza benign adult or teenager is diagnosed late or adult life. Half of the patients are asymptomatic, and radiographic diagnosis of bone abnormalities due to accident. Many patients have bone pain, neuropathy, osteoarthritis, fractures of fragile bones.
Osteopetroza infant requires treatment. Vitamin D seems to help stimulate osteoclast bone resorption and thus dormande. High doses of calcitriol and calcium intake is restricted, improved dramatically osteopetroza. Improvement is not sustained after treatment.The more practical therapy with interferon gamma on long-term benefits. Improves white cell function, decreased incidence of infection. Causes high hemoglobin, and platelet survival. Therapy in combination with calcitriol is superior. Erythropoietin is used to correct anemia. Corticosteroids are used to stimulate bone resorption and treat anemia. prednisone is administered for a few years. Osteopetroza adults do not require treatment, unless complications. Surgical therapy is necessary due to fractures or aesthetic reasons.
Osteopetroza - PathogenesisCells and bone modeling, bone remodeling:Osteoblasts synthesize bone matrix, composed predominantly of collagen type I, described in all the bone-forming surfaces.Osteoblasts are of fibroblasts. Extracellular matrix surrounding the osteoblasts that become osteocite some with critical role in bone remodeling. Osteoclasts derived from white cell line, can be attached to bone matrix and cause a compartment acidification.Acidification promotes bone bone mineral leaching.Bone modeling and remodeling are different. Remodeling involves changing the overall shape and is the largest bone in childhood and adolescence. Modeling is the medullary cavity expands as the bones grow in length and diameter. Lack remodeling underlying hematopoietic failure in osteopetroza. Remodeling involves degradation of bone out of a pre-existing bone structure and replacement with new bone synthesized.
Osteopetrozei Classification:In humans there are three distinct forms of the disease in terms of age and clinical characteristics. They are adult-onset, infantile and intermediary. Are described and other rare forms: lethal, transient, postinfectioasa, gained.A distinct form of osteopetrozei occurs in association with renal tubular acidosis and cerebral calcifications deficiency of the enzyme carbonic anhydrase. These enzymes catalyze the formation of carbonic acid from carbon dioxide and water. Lack of enzyme cause impaired bone reabsorption.
Causes and risk factors osteopetroza:The main fault in all osteopetroza is insufficient to reasorbi bone osteoclasts. Some heterogeneous molecular genetic defects cause impaired function of osteoclasts. The exact molecular defect is unknown. Specific defect is known only osteopetroza disease caused by deficiency of the enzyme: carbonic anhydrase.Osteopetroza infant appears to be autosomal recessive transmitted. In osteoclasts of patients were found viral inclusions, but still no clinical significance.