Although "Human polyomavirus 2" infection is classically associated with white matter demyelination and PML pathogenesis, recent literature has identified viral variants as etiological agents of other novel syndromes. For example, "Human polyomavirus 2" has been found to infect the granule cell layer of the cerebellum, while sparing purkinje fibers, ultimately causing severe cerebellar atrophy. This syndrome, called JCV granule cell layer neuronopathy (JCV GCN), is characterized by a productive and lytic infection by a JC variant with a mutation in the VP1 coding region.