G(M2D) GANGLIOSIDOSIS-B(1) VARIANT IN A BOY OF GERMAN HUNGARIAN DESCENT

After the introduction of iferyl-2-acetamido-2-deoxy-betaA-D-glucopyra noside (4MUG) and its sulfated form (4MUGS) in the pre- and postnatal diagnosis and carrier identification of gangliosidosis genotypes, infr equent forms of the GM2 gangliosidosis Type B (Tay-Sachs disease) have been observed which show normal activity of Hexosaminidase A (Hex A) isoenzyme with the substrate 4MUG but absent or deficient activity aga inst the sulfated form 4MUGS. Here we report the observation of a Germ an/Hungarian boy aged 12 when he died with a prolonged course of a neu rodegenerative disorder, later biochemically identified as a Gm2 gangl iosidosis B1-variant which is characterized by a deficient Hex A activ ity only against 4MUGS. The first clinical symptoms had occurred after the age of 14 months with a clear manifestation of the disease at age 3, when he presented disturbances of movement and tended to fall down . The slowly progressive course with brain atrophy, seizures and sever e mental deterioration resulted in death after almost 9 years. At auto psy, the typical light microscopic neuronal changes of a ''lysosomal s torage disorder'' were found, with multilamellar concentric bodies (MC B) and Zebra bodies in the neuronal cytoplasm at the electron microsco pic level.