Osteopetrosis

**Definition:** Osteopetrosis ('marble bone disease') is a descriptive term that refers to a group of rare, heritable disorders of the skeleton characterised by increased bone density on radiographs. Osteopetrotic conditions vary greatly in their presentation and severity, ranging from neonatal onset with life-threatening complications such as bone marrow failure (as in classical or 'malignant' autosomal recessive osteopetrosis) to the incidental finding of osteopetrosis on radiographs (e.g. osteopoikilosis).