Oligosaccharidoses and Sialic Acid Disorders
Oligosaccharidosis comprises a group of disorders which show glycoprotein excretion in urine and diminished activity of lysosomal enzymes that are involved in the degradation of sugar side chains. Among those are glycosylasparaginase deficiency (aspartylglucosaminuria), α-l-fucosidase deficiency (fucosidosis), α- and β-mannosidase deficiency (α- and β-mannosidosis), α-N-acetylgalactosaminidase deficiency (Schindler and Kanzaki disease), and neuraminidase deficiency (sialidosis). In contrast to the latter, where degradation of sialic acid containing glycosides is impaired, Salla disease results from a defect in sialin, a membrane transporter protein. Consequently, sialic acid is stored in the lysosomes. The diseases are rare and present a wide phenotypic spectrum. Detection of oligosaccharides in urine and enzyme activity measurements in leukocytes or fibroblasts is usually diagnostic. Free sialic acid has to be assessed by HPLC. For final confirmation, a molecular genetic test should be carried out. To date mainly palliative therapies can be provided.
KeywordsHematopoietic Stem Cell Transplantation Sialic Acid Enzyme Replacement Therapy Lysosomal Storage Disorder Lysosomal Storage Disease
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