gm2-gangliosidosis, ab variant gm2-gangliosidosis, ab variant gm2-gangliosidosis, ab variant is a rare, autosomal recessive metabolic disorder that causes progressive destruction of nerve cells in the brain and spinal cord. it has a similar pathology to sandhoff disease and tay–sachs disease. the three diseases are classified together as the gm2 gangliosidoses, because each disease represents a distinct molecular point of failure in the activation of the same enzyme, beta-hexosaminidase. ab variant is caused by a failure in the gene that makes an enzyme cofactor for beta-hexosaminidase, called the gm2 activator. gm2-gangliosidosis, ab variantother nameshexosaminidase activator deficiencygm2-gangliosidosis, ab variant has an autosomal recessive pattern of inheritance.specialtyneurology, medical genetics, endocrinology symptoms and signs