Sphingomyelin of red blood cells in lipidosis and in dementia of unknown origin in children.

Histological and chemical examinations of biopsy specimens from cerebral tissue of children suffering from undiagnosed progressive brain disease are performed increasingly. Important information is provided, which, though rarely of therapeutic value, does increase precision of diagnosis, prognosis, and genetic advice (Cumings, 1965a, b, c; Poser, 1962; Adams, 1965). This is especially true of the chemical investigations, and it is likely that chernical analyses will challenge the current classifications of progressive brain disease. Amaurotic idiocy has already proved to be more heterogeneous than was thought hitherto, while supposedly different diseases, such as Niemann-Pick's and gargoylism, have more in common than earlier classifications suggested. However, brain biopsy is still a procedure not to be undertaken lightly, and it would be an advantage if comparable information could be gained by a less drastic method. We have been interested in the possibility of finding abnormalities in easily 'accessible tissue, such as red blood cells, which might correlate with abnormalities in the constitution of the brain. In this paper we give the results of a study of the sphingomyelin content of erythrocytes in children with various types of progressive brain disease.