[A case of GM-Gangliosidosis (atypical form of the AB variant)].

A case of GM-gangliosidosis, variant AB, with some atypical feautres is reported in a male child, who died at the age of 4 years and 3 months. When he was 2 and a half years old, he showed signs of progressive cerebral disease with increasing motor and mental impairment. The clinical signs suggested a form of neurolipidosis; however the data of the enzymatic activities of the peripheral blood leucocytes did not show any deficit related to these forms. More specifically the values of the exosaminides A and B were normal, although the component A was near the lowest limit of the range. The anatomical, histological, histochemical, ultrastructural and chemical studies showed that it was a form of GM-gangliosidosis with visceral involvement. In the crude lipid extracts of various organs there was not only GM-ganglioside, but also a compound not previously demonstrated in these forms of neurolipidosis. Chemically this compound may be considered a phosphoglyco-lipid-and protein complex. From the enzymatic data in the peripheral blood leucocytes, the case may be a variant AB of the Sandhoff and al. classification (1971). However some clinical signs make our case closer to the 3th type of the O'Brien and al, classification while some histopathological aspects are similar to Tay-Sachs disease (i.e. to the variant B of the Sandhoff et al. classification; i.e. to the 1th type of the O'Brien et al. classification). These data, and the presence of an 'unknown compound', not yet demonstrated in the known forms of GM-gangliosidosis, support the hypothesis that our case may be considered as an 'atypical' form of the variant AB of the gangliosidosis GM and that further studies are necessary to reach a final nosography of these entities.