GM2 activator protein deficiency, mimic of Tay-Sachs disease

GM2 Gangliosidoses are a group of autosomal recessive genetic disorders caused by intra-lysosomal deposition of ganglioside GM2 mainly in the neuronal cells.GM2-Activator protein deficiency is an extremely rare type of GM2 gangliosidosis (AB variant) caused by the mutation of GM2A.We report a case of a female child who presented with clinical features similar to classical Tay-Sachs disease, but with normal beta hexosaminidase enzyme levels. Molecular study revealed a novel homozygous intronic mutation which confirmed the diagnosis of GM2 Activator protein deficiency. GM2 Activator protein deficiency is a mimic of Classical Tay-Sachs disease and should be a differential diagnosis in children who present with neuroregression, cherry red spots without hepatosplenomegaly and with normal beta hexosaminidase enzyme levels.