Studies on human β D N acetylhexosaminidases. III. Biochemical genetics of Tay Sachs and Sandhoof's diseases

Tay Sachs disease is an inherited disorder in which β D N acetylhexosaminidase activity is absent. Sandhoff's disease is a clinically identical disorder in which both hexosaminidase A and hexosaminidase B activity is missing. Antibodies to purified hexosaminidase A and hexosaminidase B were produced in rabbits. Each antiserum was reactive against both isozymes on immunodiffusion. No hexosaminidase A antigen was present in the livers of the 2 Tay Sachs disease patients and only a possible trace of antigen was found in the third case. The liver from one patient with Sandoff's disease contained both hexosaminidase A and hexosaminidase B antigens, even though no enzymatic activity was present, whereas the liver from the other patient with Sandhoff's disease contained only hexosaminidase A antigen. It is suggested that hexosaminidase A and hexosaminidase B share a common subunit and the other subunit in the 2 hexosaminidases may be different.