[Enzymatic diagnosis and clinical characteristics of 52 children with mucopolysaccharidosis].

Objective: To explore the incidence of various types of mucopolysaccharidosis (MPS) and their clinical characteristics.

Methods: A total of 75 children highly suspected as having MPS underwent quantitative and electrophoretic analysis of urinary glycosaminoglycans (GAGs) and enzymatic analysis of seven types of MPS from January 2009 to December 2011. Fluorescence assay was used to measure the activities of α-L-iduronidase, iduronate-2-sulfatase, α-N-acetylglucosaminidase, galactosamine-6-sulfatase, β-galactosidase, arylsulfatase B and β-glucuronidase in the white blood cells.

Results: A total of 52 cases were confirmed with MPS based on clinical, radiological, and enzymatic examinations. The 52 cases, with a mean age of 4.0 ± 2.2 years, included 5 cases of MPS I (10%), 20 cases of MPS II (38%), 20 cases of MPS IVA (38%), 6 cases of MPS VI (12%) and 1 case of MPS VII (2%). No MPS IV B cases or MPS IIIB cases were found. Compared with healthy children of the same age, the GAG/Cr ratio was significantly elevated in 50 confirmed cases of MPS (two MPS IVA cases having no increased ratio). All children with increased urinary GAGs had a confirmed diagnosis of MPS. The age of onset was between 1 and 2 years after birth in most cases, and often complicated by hernia and valvular heart disease. Children with MPS I, MPS II, and MPS VI presented with ugly and unsmooth face, short stature, joint stiffness, and limitation of motion, while children with MPS IVA presented with short stature, skeletal dysplasia, and joint laxity.

Conclusions: Type IVA and type II are the most common in MPS cases, followed by type VI and type I. MPS children are characterized by special appearances including ugly and unsmooth facial appearance, short stature and skeletal dysplasia. Quantitative analysis of urinary GAG, as a simple, rapid, and reliable method, is recommended for screening of MPS.