The Effects of Enzyme Replacement Therapy in Patients with Mucopolysaccharidosis Type 1: A Case Series Study

Mucopolysaccharidosis type I (MPS1) is caused by mutations in the gene which encodes the enzyme alpha-L-iduronidase. Deficiency of this enzyme causes a range of clinical symptoms in patients. The main treatment for MPS1 is hematopoietic stem cell transplantation. But its morbidity and mortality rates are significant and require matched marrow donors. Another method of treating MPS1 is enzyme replacement therapy (ERT). This study was performed to determine the effects of ERT in patients with MPS1. Seven patients with MPS1, admitted in Imam Reza Hospital of Mashhad, Iran, during 2014, were included in the study. They were treated with a single dose (0.58 mg/kg) of enzyme laronidase and followed in 0, 3, 6, 9 and 12 months. The urinary glycosaminoglycan’s (GAG), shoulder and elbow joint range of motion, volume of liver and spleen, and six-minute walking test were evaluated. Data was analyzed by SPSS software (version 16.0). The mean age of the patients was 22.43±5.85 months at the baseline. During follow-up, the level of urinary GAG showed a significant reduction (p=0.004), the volumes of liver (p<0.001) and spleen (p=0.004) were significantly reduced, and the result of 6-minute walking test was significantly increased (p<0.001). The side effects included generalized skin erythema as an allergic reaction in one patient and two episodes of fever during drug administration in one patient. According to the results, the treatment with L-iduronidase in patients with MPS1 was effective and mostly safe.