Sialidoses

Abstract

Sialidoses are autosomal recessive disorders caused by NEU1 gene mutations and are classified on the basis of their phenotype and onset age. Sialidosis type II, with infantile onset, has a more severe phenotype characterized by coarse facial features, hepatomegaly, dysostosis multiplex, and developmental delay while patients with the late and milder type, known as “cherry red spot‐myoclonus syndrome” develop myoclonic epilepsy, visual impairment and ataxia in the second or third decade of life. The diagnosis is usually suggested by increased urinary bound sialic acid excretion. We recently described genetically diagnosed patients with a specially mild phenotype, no retinal abnormalities and normal urinary sialic acid. This observation suggests that genetic analysis or the demonstration of the neuraminidase enzyme deficiency in cultured fibroblasts are needed to detect and diagnose mildest phenotypes.

Sialidosis: A Review of Morphology and Molecular Biology of a Rare Pediatric Disorder

“…Precipitating factors may include light touch, sound stimuli, voluntary movements, passive joint movements, voluntary movements, and dysarthria. Action myoclonus, intentional tremors, cerebellar ataxia, and hyperreflexia are the other commonly found symptoms [ 14 ]. Muscle strength may remain normal.…”

Abnormal Sphingolipid World in Inflammation Specific for Lysosomal Storage Diseases and Skin Disorders

“…Lysosomal sialidase (EC 3.2.1.18) has a dual physiological function; it participates in the intra-lysosomal catabolism of sialylated glycoconjugates and is involved in cellular immune response. Mutations in the sialidase gene NEU1 result in an autosomal recessive disorder, sialidosis (OMIM 256550), which is characterized by the progressive lysosomal storage of sialylated glycopeptides and oligosaccharides [ 43 , 44 ]. Sialidoses are classified on the basis of their phenotype and onset age.…”

“…Type I patients develop visual defects, myoclonus syndrome, cherry-red macular spots, hyperreflexia and seizures. Individuals with the late and milder type develop visual impairment and ataxia in the second or third decade of life [ 44 ].…”

Transcranial magnetic stimulation as a tool to understand genetic conditions associated with epilepsy

“…Sialidosis is an autosomal recessive lysosomal storage disorder caused by mutations in the NEU1 gene, which encodes a lysosomal neuraminidase. 74 Type I sialidosis is a progressive myoclonic epilepsy with onset in the second or third decade; characteristics include macular changes known as 'cherryred spots' and ataxia. 74 Compared to controls, 12 individuals with sialidosis I had greater MEP amplitudes, while SICI and CSP duration were significantly reduced.…”

“…74 Type I sialidosis is a progressive myoclonic epilepsy with onset in the second or third decade; characteristics include macular changes known as 'cherryred spots' and ataxia. 74 Compared to controls, 12 individuals with sialidosis I had greater MEP amplitudes, while SICI and CSP duration were significantly reduced. 75 The findings were thought to be in keeping with increased excitability and reduced GABA A ergic, and possibly also GABA B ergic, inhibition.…”