Clinical and Epidemiological Characteristics of Patients with Mucopolysaccharidosis Type II (Hunter Syndrome) According to Data from the Russian Registry

Background. The study was conducted based on data from the Russian registry of patients with mucopolysaccharidosis (MPS) type II. There are no similar studies based on analysis of data from the national MPS registry in Russian Federation.

Objective. The aim of the study is to conduct a comprehensive analysis of MPS type II epidemiology and phenotypic features in Russian patients using data from the national registry, as well as to compare the obtained results with corresponding data from international registries.

Methods. The retrospective, cross-sectional observational study included data from 177 patients with confirmed diagnosis of MPS type II. Data on medical history, clinical, laboratory, and instrumental examination methods, as well as data on enzyme replacement therapy (ERT) over the period from 2008 to March 2026 was analyzed.

Results. The prevalence of MPS type II in Russian Federation was 0.1 per 100,000 population, and 0.54 per 100,000 live births (approximately 1 in 185,000 live births). The geographical distribution of patients was uneven. The median age of first symptoms was 1.0 (0; 2.0) years, the range — from the first months of life to 23 years, and the median age of established diagnosis was 3.0 (2.0; 6.0) years, the range — from 0.1 to 38.9 years. The major symptoms of MPS type II in children at the time of diagnosis included musculoskeletal disorders (99.1%), Hurler phenotype 96.4%, short neck was detected in 88.8%, hepatomegaly (based on physical examination findings) in 91.9% of patients, according to abdominal ultrasound data in 87.7% patients, umbilical and inguinal hernias in 82.1% of patients, cardiovascular damage — in 80.3%, chest deformity — 80.3%, contractures of the hand joints (74.5%), and ENT manifestations (62.4%). 151 (85.3%) patients were alive at the time of data collection. ERT was administered to 140 out of 160 (87.5%) patients with MPS type II. Frequent variants in the IDS gene typical for the Russian population were revealed: recombination IDS/ps IDS2 ex3/int7, variants p.Gly374=, p.Arg468Gln, p.Ala85Thr, p.Pro86Leu and p.Arg443Ter.

Conclusion. The prevalence of MPS type II in Russian Federation is comparable to data from international registries. The registry-based approach enables the dynamic analysis of the disease’s clinical signs, treatment efficacy evaluation, and planning of healthcare resources. Further expansion of clinical part of the registry, regular data updates, and integration with international registry platforms are crucial for in-depth research and for obtaining more comprehensive data on patients with orphan diseases.

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