Variable phenotype and severity of sialidosis expressed in two siblings presenting with ataxia and macular cherry-red spots.

Sialidosis is a rare lysosomal storage disease with a wide clinical spectrum ranging from nearly asymptomatic to severe presentations. We present two Brazilian siblings with sialidosis, the first patient with sialidosis type I, and the second with sialidosis type II. Our report reinforces the relevance of ophthalmologic evaluation in patients with early and late-onset ataxias, if an association with myoclonus or dysmorphic features is present or not. Also, we demonstrate that sialidosis might represent a single genetic entity with variable clinical expression through these two siblings.