Osteopetrosis
Osteopetrosis is a term that refers to a group of rare
disorders of the skeletal system characterized by increased bone mass (density)
as seen on X-ray images. Sometime referred to as Marble Bone Disease,
osteopetrosis may be inherited and because of the high
density, bone becomes brittle causing multiple bone fractures and in some cases,
skeletal abnormalities.
ADO*, autosomal dominant osteopetrosis occurs 1 in 20,000
births (0.005%) and is more prevalent than ARO*, autosomal recessive
osteopetrosis, which occurs 1 in 250,000 births (0.0004%).
The root cause of osteopetrosis is failure of osteoclasts*
(a special kind of bone modeling cells) function as a result of mutations in
multiple genes human. The infantile form, the intermediate form and the adult
form are three major types of osteopetrosis. The infantile form is severer than
other forms. If left untreated it can diminish life expectancy of the infant due
to bone marrow failure. Adult form is milder and the life expectancy is normal.
The intermediate form is found in young children is less severe than the
infantile form.
The symptoms of osteopetrosis is diverse, from infantile
life threatening marrow failure to casual bone fractures in adults. Symptoms
include pancytopenia (a over all reduction in various types of blood cell
numbers), neuropathy (peripheral nervous system conditions).
Trivial injuries may result in bone fractures due to
hardening of the bone thus incidentally exposing adult form of osteopeterosis,
which otherwise may have gone unnoticed.
Though there is no cure is available yet, in severe infantile forms, where
bone marrow fails, hematopoietic stem cell transplantation is employed. The drug
erythropoietin may help in alleviating anemia. Vitamin D might help with
hypocalcimia.
A German radiologist, Albers-Schönberg, first
described it in 1904.
*ADO – Only one of the two genes to be defective for
disease onset.
*ARO – Both genes to be defective for disease onset.
*osteoclasts – a
bone resorbing type of cells work in balance with osteoblasts, a special kind of
bone forming type of cells.
