Mucopolysaccharidosis Type I in the Russian Federation and Other Republics of the Former Soviet Union: Molecular Genetic Analysis and Epidemiology.

Mutations in the IDUA gene cause deficiency of the lysosomal enzyme alpha-l-iduronidase (IDUA), which leads to a rare disease known as mucopolysaccharidosis type I. More than 300 pathogenic variants of the IDUA gene have been reported to date, but not much is known about the distribution of mutations in different populations and ethnic groups due to the low prevalence of the disease. This article presents the results of a molecular genetic study of 206 patients with mucopolysaccharidosis type I (MPS I) from the Russian Federation (RF) and other republics of the former Soviet Union. Among them, there were 173 Russian (Slavic) patients, 9 Tatars, and 24 patients of different nationalities from other republics of the former Soviet Union. Seventy-three different pathogenic variants in the IDUA gene were identified. The common variant NM_000203.5:c.208C>T was the most prevalent mutant allele among Russian and Tatar patients. The common variant NM_000203.5:c.1205G>A accounted for only 5.8% mutant alleles in Russian patients. Both mutations were very rare or absent in patients from other populations. The pathogenic variant NM_000203.5:c.187C>T was the major allele in patients of Turkic origin (Altaian, Uzbeks, and Kyrgyz). Specific own pathogenic alleles in the IDUA gene were identified in each of these ethnic groups. The identified features are important for understanding the molecular origin of the disease, predicting the risk of its development and creating optimal diagnostic and treatment tools for specific regions and ethnic groups.

Transition of patients with mucopolysaccharidosis from paediatric to adult care.

Mucopolysaccharidoses (MPS) are rare disorders associated with enzyme deficiencies, resulting in glycosaminoglycan (GAG) accumulation in multiple organ systems. As patients increasingly survive to adulthood, the need for a smooth transition into adult care is essential. Using case studies, we outline strategies and highlight the challenges of transition, illustrating practical solutions that may be used to optimise the transition process for patients with MPS disorders. Seven MPS case studies were provided by four European inherited metabolic disease centres; six of these patients transferred to an adult care setting and the final patient remained under paediatric care. Of the patients who transferred, age at the start of transition ranged between 14 and 18 years (age at transfer ranged from 16 to 19 years). While there were some shared features of transition strategies, they varied in duration, the healthcare professionals involved and the management of adult patients with MPS. Challenges included complex symptoms, patients' unwillingness to attend appointments with unfamiliar team members and attachment to paediatricians. Challenges were resolved by starting transition at an early age, educating patients and families, and providing regular communication with and reassurance to the patient and family. Sufficient time should be provided to allow patients to understand their responsibilities in the adult care setting while feeling assured of continued support from healthcare professionals. The involvement of a coordinated multidisciplinary team with expertise in MPS is also key. Overall, transition strategies must be comprehensive and individualised to patients' needs.

[Sanfilippo Syndrome].

Sanfilippo syndrome (mucopolysaccharidosis type III) is a lysosomal disorder caused by a defect in the catabolism of heparan sulfate. Mucopolysaccharidosis type III is the most common type of all mucopolysaccharidoses. The pathogenic basis of the disease consists of the storage of undegraded substrate in the central nervous system. Progressive cognitive decline resulting in dementia and behavioural abnormalities are the main clinical characteristics of Sanfilippo syndrome. Mucopolysaccharidosis type III may be misdiagnosed as otherforms of developmental delay, attention deficit/hyperactivity disorder and autistic spectrum disorders because of lack of somatic symptoms, presence of mild and atypical forms of the disease. Patients with Sanfilippo syndrome may have comparatively low urinary glycosaminoglycans levels resulting in false negative urinary assay. Definitive diagnosis is made by enzyme assay on leucocytes and cultured fibroblasts. There is currently no effective treatment of mucopolysaccharidosis type III, though ongoing researches of gene, substrate reduction and intrathecal enzyme replacement therapies expect getting curative method to alter devasting damage of central nervous system in near future.