Osteopetrosis

Osteopetrosis, literally 'stone bone', also known as marble bone disease or Albers-Schönberg disease, is an extremely rare inherited disorder whereby the bones harden, becoming denser, in contrast to more prevalent conditions like osteoporosis, in which the bones become less dense and more brittle, or osteomalacia, in which the bones soften. Osteopetrosis can cause bones to dissolve and break.EDAR (EDAR hypohidrotic ectodermal dysplasia) Osteopetrosis, literally 'stone bone', also known as marble bone disease or Albers-Schönberg disease, is an extremely rare inherited disorder whereby the bones harden, becoming denser, in contrast to more prevalent conditions like osteoporosis, in which the bones become less dense and more brittle, or osteomalacia, in which the bones soften. Osteopetrosis can cause bones to dissolve and break. It is one of the hereditary causes of osteosclerosis. It is considered to be the prototype of osteosclerosing dysplasias. The cause of the disease is understood to be malfunctioning osteoclasts, and its inability to resorb bone. Although human osteopetrosis is a heterogeneous disorder encompassing different molecular lesions and a range of clinical features, all forms share a single pathogenic nexus in the osteoclast. The exact molecular defects or location of the mutations taking place are unknown. Osteopetrosis was first described in 1903, by German radiologist Albers-Schönberg. Despite this excess bone formation, people with osteopetrosis tend to have bones that are more brittle than normal. Mild osteopetrosis may cause no symptoms, and present no problems. However, serious forms can result in... Autosomal recessive osteopetrosis (ARO), also known as malignant infantile osteopetrosis, is a rare type of skeletal dysplasia characterized by a distinct radiographic pattern of overall increased density of the bones with fundamental involvement of the medullary portion. Infantile osteopetrosis typically manifests in infancy. Diagnosis is principally based on clinical and radiographic evaluation, confirmed by gene analysis where applicable. As a result of medullary canal obliteration and bony expansion, grave pancytopenia, cranial nerve compression, and pathologic fractures may ensue. The prognosis is poor if untreated. The classic radiographic features include, endobone or 'bone-within-bone' appearance in the spine, pelvis and proximal femora, upper limbs, and short tubular bones of the hand. Additionally, there is the Erlenmeyer flask deformity type 2 which is characterized by absence of normal diaphysial metaphysical modeling of the distal femora with abnormal radiographic appearance of trabecular bone and alternating radiolucent metaphyseal bands. The precise and early diagnosis of infantile osteopetrosis is important for management of complications, genetic counselling, and timely institution of appropriate treatment, namely hematopoietic stem cell transplantation (HSCT), which offers a satisfactory treatment modality for a considerable percentage of infantile osteopetrosis. Amelioration of radiographic bone lesions after HSCT in infantile osteopetrosis has been proposed as an important indicator of success of the therapy. A few publications with limited study participants have demonstrated the resolution of skeletal radiographic pathology following HSCT. Autosomal dominant osteopetrosis (ADO) is also known as Albers-Schonberg disease. Most do not know they have this disorder because most individuals do not show any symptoms. However, the ones that do show symptoms will typically have a curvature of the spine (scoliosis), and multiple bone fractures. There are two types of adult osteopetrosis based on the basis of radiographic, biochemical, and clinical features. Many patients will have bone pains. The defects are very common and include neuropathies due to cranial nerve entrapment, osteoarthritis, and carpal tunnel syndrome. About 40% of patients will experience recurrent fractures of their bones. 10% of patients will have osteomyelitis of the mandible. The various types of osteopetrosis are caused by genetic changes (mutations) in one of at least ten genes. There is nothing a parent can do before, during or after a pregnancy to cause osteopetrosis in a child.