Mucopolysaccharidosis type II (Hunter syndrome, MPS II, OMIM 309900) is an X-linked lysosomal storage disorder caused by deficiency of iduronate-2-sulfatase (IDS). We analyzed clinical and laboratory data from 44 Slavic patients with this disease. In total, 21 Czech, 7 Slovak, 9 Croatian and 7 Serbian patients (43 M/1 F) were included in the study (median age 11.0 years, range 1.2-43 years). Birth prevalence ranged from 1:69,223 (Serbia) to 1:192,626 (Czech Rep.). In the majority of patients (71%), the disease manifested in infancy. Cognitive functions were normal in 10 patients. Four, six and 24 patients had mild, moderate, and severe developmental delay, respectively, typically subsequent to developmental regression (59%). Residual enzyme activity showed no predictive value, and estimation of glycosaminoglycans (GAGs) had only limited importance for prognosis. Mutation analysis performed in 36 families led to the identification of 12 novel mutations, eight of which were small deletions/insertions. Large deletions/rearrangements and all but one small deletion/insertion led to a severe phenotype. This genotype-phenotype correlation was also identified in six cases with recurrent missense mutations. Based on patient genotype, the severity of the disease may be predicted with high probability in approximately half of MPS II patients.

1st Department of Pediatrics Comenius University Medical School in Bratislava University Children's Hospital Bratislava Slovakia

2nd Department of Pediatrics Comenius University Medical School in Bratislava University Children's Hospital Bratislava Slovakia

Department of Laboratory Diagnostics University Hospital Centre Zagreb and School of Medicine Zagreb Croatia

Department of Metabolism and Clinical Genetics Mother and Child Health Care Institute of Serbia Belgrade Serbia

Department of Paediatrics and Adolescent Medicine 1st Faculty of Medicine Charles University and General University Hospital Prague Czech Republic

Department of Paediatrics Children's Hospital Zagreb School of Medicine Zagreb Croatia

Department of Pediatrics University Hospital Center and University of Zagreb School of Medicine Zagreb Croatia

Department of Pediatrics University Hospital Center Zagreb Croatia

Institute of Inherited Metabolic Disorders 1st Faculty of Medicine Charles University and General University Hospital Prague Czech Republic

School of Medicine University of Belgrade Belgrade Serbia

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