Lysosomal storage diseases: mucopolysaccharidosis type I and II

Abstract

Mucopolysaccharidosis (MPS) are a genetically heterogeneous group of rare monogenic metabolic diseases associated with hereditary insufficiency of lysosomal enzymes involved in the catabolism of glycosaminoglycans, or mucopolysaccharides. The pathogenesis of MPS is due to the accumulation of non-cleaved glycosaminoglycans in lysosomes, which can destroy cells. All MPS are characterized by a polysystemic manifestation, the simultaneous involvement of many organs and tissues in the pathological process, first of all, connective tissues, bones and cartilaginous. This review presents the epidemiology, clinical, biochemical, and molecular genetic characteristics of MPS types I and II, caused by the recessive mutations in the alpha-L-iduronidase and iduronate-2-sulfatase genes, respectively, and by the accumulation of dermatan and heparan sulfate. Each of these diseases is characterized by clinical polymorphism, especially observed in MPS I, which often manifests in a severe form of Hurler syndrome, but can also occur in a milder form of Scheie syndrome. Currently, there is an increased interest in MPS in the world due to the identification of the spectrum and frequencies of mutations in theIDUAandIDSgenes in various populations, including in Russia, and the practical availability of methods for individual molecular diagnostics. The description of the existing experimental models, their role in the study of the biochemical basis of the pathogenesis of these severe hereditary diseases and the development of various therapeutic approaches are given. Discusses the possibility of early diagnosis of MPS I and II types based on neonatal screening in order to increase the effectiveness of their prevention and treatment, as well as the advantages and disadvantages of the main approaches to the treatment of these serious diseases, such as hematopoietic stem cell transplantation, enzyme replacement and substrate-reducing therapy. A clinical example of a combination therapy for a severe form of mucopolysaccharidosis type I Hurler syndrome is presented