A CONGENITAL FORM OF AMAUROTIC FAMILY IDIOCY.

SINCE the original description of Tay-Sach's disease in the eighties of the last century a group of allied nervous disorders has become recognized, the common pathological feature of which is a ubiquitous distention of the nerve cells with granules of a lipoid nature. Apart from a few anomalous forms it is customary to classify these amaurotic family idiocies according to the time of onset of the disease, infantile, late infantile, juvenile, late juvenile and adult types being described. The resemblance between the infantile type and Niemann-Pick's disease had been noted by Knox, et alia, in 1916, but it was not until Pick and Bielschowsky's (1927, 1928) demonstration of the closely similar cerebral pathologies of these two conditions that it became generally realized that disordered lipoid metabolism, not heredodegeneration, was responsible for the granular accumulations in the nerve cells. The consequent inclusion of the amaurotic family idiocies in the category of lipoidoses began a new chapter in the history of these much studied diseases and support for this new theory of pathogenesis has since been received from the occasional finding ofthe characteristic type of neuronal swelling in the predominantly mesodermal disorders of Gaucher (Lindau, 1930) and of Hunter-Hurler (Ashby, et alia, 1937). Nevertheless, in many, perhaps most, cases of amaurotic family idiocy lipoid storage is confined to the nervous system, and it might well seem a perversion of nomenclature to classify these apparently purely nervous diseases as " lipoidoses" were it not that in some otherwise typical examples of the infantile and juvenile forms unsuspected lipoid storage in the visceral organs has been found on microscopical search (Schob, 1930; Pick, 1932; Brouwer, 1936). The case recorded in this paper belongs to this theoretically important intermediate group which is characterized by the predominantly cerebral localization of the lipoid deposition, the reticulo-endothelial system being involved only in a minor degree. It differs, however, from Tay-Sach's disease in several respects, notably in its congenital character and in the histochemical reactions of the intracellular lipoid. 175 coright.