Clinical and genetic characteristics of mucopolysaccharidosis type VI according to the Russian registry

BACKGROUND Mucopolysaccharidosis type VI (MPS VI) is a chronic, progressive, inherited disease with multiorgan involvement and a restricted life expectancy. AIM To investigate the epidemiological, clinical, and genetic characteristics of patients with mucopolysaccharidosis type 6 and their outcomes using the Russian Federation's national registry, as per the Russian registry, and compare them with previously published data. METHODS In a retrospective cohort study, clinical, laboratory data, molecular genetic analysis results, and enzyme replacement therapy (ERT) data were extracted and analyzed from the Russian MPS VI registry for 53 patients, comprising 26 males (49.1%) and 27 females (50.9%). RESULTS The median age of first symptoms was 2 years, ranging from the first months of life to 20 years. A positive family history of MPS VI was reported in 19/53 (35.8%) patients, a negative family history in 24 (45.3%), and missing information in 10 (18.9%). The main features of the disease were hepatomegaly (n = 23; 60.5%), splenomegaly (n = 15, 39.5%), involvement of otolaryngological organs (n = 24/33; 72.7%), umbilical and inguinal hernia (n = 19/36; 52.8%), heart involvement (n = 26/32; 81.3%) with valve involvement (n = 25/26; 96.2%) and linear growth delay (n = 30/39, 76.9%). Two patients (3.8%) died. The most common variants identified in the ARSB gene were c.454C>T and c.194C>T. At the time of data collection, ERT had ever received 48/53 (90.5%) patients. CONCLUSION No correlation was observed between the age of onset of the first symptoms, the severity of clinical manifestations, enzyme activity, or nucleotide variants in the ARSB gene.