GM2A, also known as ganglioside GM2 activator, encodes a transport protein essential for degrading GM2 gangliosides into their GM3 form within the cell's lysosomes. Mutations in GM2A lead to AB-Variant GM2 gangliosidosis, a rare lysosomal storage disorder. GM2A's function is crucial in the context of GM2 ganglioside metabolism, a pathway relevant to neurodegenerative lysosomal storage disorders [1,2,3].

Gm2a-/-mice, a model of ABGM2, exhibit phenotypes representative of the predicted adult-onset form with moderate GM2 accumulation and mild neurological defects. This mild phenotype is due to compensation by the sialidase, neuraminidase 3 (NEU3)-mediated alternative GM2 degradation pathway, which is more prominent in mice than humans. Double knock-out (Gm2a-/-Neu3-/-) mice present a more severe ABGM2-like phenotype, including ataxia, reduced mobility, weight loss, and lethality, along with increased GM2 accumulation in the CNS. This indicates the role of GM2A in preventing excessive GM2 ganglioside accumulation and subsequent neurodegeneration [3].

In conclusion, GM2A is vital for GM2 ganglioside degradation, and its deficiency leads to AB-Variant GM2 gangliosidosis. The use of Gm2a-/-and Gm2a-/-Neu3-/-mouse models has been instrumental in understanding GM2A's role in preventing neurodegeneration associated with GM2 ganglioside accumulation, providing insights into the disease mechanism and potential for pre-clinical drug studies [3].