Osteopetrosis is characterized by the failure of osteoclasts to resorb bone. As a result, bones become thickened and dense. Despite this increased mass, bones have increased fragility. The increased bone mass can also lead to hematopoietic insufficiency.
NEMO deficiency - A severe form of this disease exhibiting osteopetrosis and lymphedema has been reported in a small number of patients. Two patients were found to have the same X420W mutation in the NEMO gene.