Background: Mucopolysaccharidosis (MPS) can be classified into 7 types according to the enzyme defects. Several countries use enzyme replacement therapy (ERT) as treatment for types 1, 2 and 6. ERT is very expensive: - therefore, to determine if this treatment could be made available in Thailand, it is important to know the numbers of the patients with MPS.
Objectives: To investigate the number and clinical profiles of MPS patients who visited the Queen Sirikit National Institute of Child Health (QSNICH) to determine the incidence of MPS in Thailand.
Material and Method: Review of MPS patients’ medical records with confirmed diagnosis by enzyme tests, who visited QSNICH from January 1999 to December 2013.
Results: Medical records showed that 22 MPS patients visited QSNICH during the past 15 years. Of these patients, 5 were MPS 1 patients (intermediate type or Hurler-Scheie syndrome), 8 were MPS2 patients (severe form), 1 was a MPS3 patient, 2 were MPS4 patients and 6 were MPS6 patients (severe form). The first clinical sign observed in MPS1 is joint contracture, whereas in MPS2 is delayed development. For MPS2, all except one patient had macrocephaly (head circumference is more than 90 percentile). Other growth parameters, including weight and height, in MPS2 patients were higher than average (>50 percentile).
Conclusion: MPS2 is the most common type of MPS in this study, followed by type 6 and 1. The difference in growth parameters seen in MPS2 suggest that it may be a factor in the development of MPS2.

Keywords: Enzyme replacement therapy, Hunter syndrome, Hurler syndrome, Incidence, Maroteaux-lamy syndrome, Mucopolysaccharidosis, Overgrowth