Contiguous gene syndrome in severe case of mucopolysaccharidosis type II

This article presented below reflects modern ideas about the combination of several hereditary syndromes as a result of an contiguous deletion of the X chromosome by the example of mucopolysaccharidosis type II and mental retardation. Monogenic syndromes occurring in the literature in combination, marked as contiguous gene syndromes, have been analyzed, along with what the notion of contiguous geneshas been described. Contiguous gene syndromes due to the deletion of the X chromosome region in boys lead to structural and functional nullisomy, thus confirming the significance of studying the number of copies of genes in order to determine the exact genetic defect. The data of the literature and our own observations concerning issues of etiology, pathogenesis, time of manifestation and clinical symptoms of the disease, diagnostic methods, treatment and prevention of mucopolysaccharidosis type II are summarized. Mucopolysaccharidosis type II refers to а group of lysosomal storage diseases with multiorgan lesions. Here is described a clinical case of Hunter syndrome with a long deletion of the X chromosome and an early manifestation of a combined stenosis of the spinal canal, the development of myelopathy of the cervical spinal cord as a result of the accumulation of glycosaminoglycans in the membranes of the spinal cord. The described case with the clinical picture of mixed tetraparesis is a rarer symptom with type II mucopolysaccharidosis than with other mucopolysaccharidosis and, as a rule, manifests at an older age. It was suggested that such a phenotypic correlation in patients with mucopolysaccharidosis type II, as a severe phenotype with neurological symptoms with a complete deletion of the IDS gene. The algorithm for examining patients with non-syndromic mental retardation includes the analysis of karyotype, DNA-diagnosis of fragile X chromosome, and chromosome analysis. It is shown that a survey is needed to exclude MPS II in boys with mental retardation and the inclusion of simple biochemical tests in these algorithms - determination of GAG in urine and analysis of lysosomal enzymes, which will more effectively identify patients with MPS type II.

Синдром Хантера, мукополисахаридоз II типа, X хромосома, делеция, наследственные синдромы, умственная отсталость, «сопряженные» генные синдромы, Hunter syndrome, mucopolysaccharidosis type II, X chromosome, deletion, hereditary syndromes, mental retardation, contigious gene syndrome

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