This defect causes bones throughout the body to become excessively dense and to fracture easily. Osteopetrosis is the most severe form of the disease.
Affected children tend to be short but with relatively large heads.
They often sustain birth fractures and may be jittery or fit during the first month of life due to a low blood calcium. Many children become blind by 6 months of age, deafness and hydrocephalus may develop later. Without treatment many affected children die before adolescence. However, in those for whom suitable donors can be found, bone marrow transplantation may be curative. Alternatively, injections of gamma interferon may alleviate some symptoms of the disease.