What is Osteopetrosis?
Osteopetrosis, also known as Marble Bone Disease or Albers-Schonberg disease, is an extremely rare, inherited disorder caused by mutations on the CLCN7 gene whereby the bones harden, becoming denser.
Bone growth is a balance between osteoblasts (cells that create new bone tissue) and osteoclasts (cells that destroy old bone tissue). Sufferers of osteopetrosis have impaired osteoclasts function; meaning old bone tissue is not destroyed and removed from the body. This results in bones that are denser and more brittle than normal bones. Mild forms of osteopetrosis may cause no symptoms and present no problems; however, more severe forms can result in stunted growth, deformity, increased likelihood of fractures, bone infection, enlarged spleen, kidney problems, anemia, and other blood issues. Osteopetrosis can also lead to blindness, facial paralysis, and deafness; due to the increased pressure put on the nerves by the extra bone.
Autosomal Recessive Osteopetrosis (ARO)
ARO is also known as Malignant Infantile Osteopetrosis because it is diagnosed immediately or shortly after birth and is fatal if left untreated. As stated, ARO occurs when a person inherits two copies of the mutated CLCN7 gene from their parents. A person with ARO is born with extremely brittle bones and 75% of those afflicted will develop hematological problems such as, anemia, thrombocytopenia, and granulocytopenia in their first year of life. Compression of the cranial nerves in ARO patients often leads to blindness and deafness and other symptoms include frequent bone fractures, infections, and low calcium levels that may cause seizures. A bone marrow transplant is the only known treatment for ARO and without treatment most ARO patients will not live past the age of ten.
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