The Tarantula
Sialidosis & Galactosialidosis
Due to clinical features, these two clinical pictures are hardly distinguishable. Sialidosis is caused by a lysosomal neuramidase deficiency. Galactosialidosis is characterized by a deficiency of lysosomal neuraminidase and b-galactosidase. This is caused by a lack of an activator and transport protein for these two enzymes. Initially, this enzyme was called protective protein. Later, the protective protein was also characterized as Cathepsin A. Initially the children with sialidosis type II or galactosialidosis resemble children with MPS 1 (Hurler phenotype). The course especially in late infantile and juvenile forms can be complicated by renal failure with proteinuria. Probably the Hydrops fetalis is the most frequent and most severe manifestation of the disease. Sialidosis type I, also called Cherry Red Spot Myoclonus Syndrome, is associated without the changes observed in MPS. In late childhood or adolescence, there is loss of visual acuity, polymyoclonus and seizures.
