THE DIAGNOSIS OF TAY‐SACHS DISEASE1

Summary Gangliosides and neutral aminoglycolipids were determined in several organs from two subjects with classical Tay‐Sachs disease. Ganglioside GM2 was stored in all organs investigated. Of the extraneural organs, the highest concentration was found in the adrenals, spleen and liver. The rectal muscular layer had a high concentration of gangliosides. Rectal biopsy might be used for studies of the nervous ganglioside pattern. The brain tissue showed a many‐fold increase of the activities of p‐nitrophenylglycosi‐dases. The activity of ganglioside sialidase in the brain was not increased in Tay‐Sachs and some other neurometabolic diseases. Subfrac‐tionation of the glycohydrolases by ultracen‐trifugation showed no hexosaminidase activity in the supernatant fraction of the brain in Tay‐Sachs disease compared with about 2/3 of the total activity in normal human brain. A simple agarose electrophoretic method was developed for the separation of the hexosaminidases into two fractions, A and B. Hexosaminidase A was virtually absent in Tay‐Sachs disease. The known forms of gangliosidoses and their biochemical characteristics are reviewed and a scheme is given for their classification and diagnosis.