Partial deficiency of beta-hexosaminidase activity in canine GM2-gangliosidosis.

4-Methylumbelliferyl-N-acetylglucosamine-6-sulfate (4MUGLc6S) which is known to be a specific substrate for human hexosaminidase A was used to determine enzymatic features of canine GM2-gangliosidosis. The enzyme activity using 4MUGlc6S in affected dog brain and liver was less than 20 to 30% of control tissues, whereas total 4-methylumbelliferyl beta-glucosaminidase activity in canine GM2-gangliosidosis was normal or elevated. However, when beta-hexosaminidase was fractionated by DEAE-Sepharose column chromatography, beta-hexosaminidase A like fraction in affected dog tissues was reduced to 20 to 30% of control. These data suggest that canine GM2-gangliosidosis is analogous to human juvenile.