Infantile osteopetrosis and neuronal storage disease.

Infantile osteopetrosis often presents with neurologic symptoms that cannot always be attributed to primary bone disease of the skull. We studied an infant with osteopetrosis and pathologic evidence of neuronal and axonal changes. This is the third case in which primary parenchymal disease of the brain was associated with infantile osteopetrosis and the first in which neuronal cytoplasmic storage was documented by light and electronmicroscopy. The simultaneous occurrence of two rare autosomal-recessive disorders, each possibly caused by an inherited lysosomal enzyme deficiency, may not be fortuitous.