Hunter Syndrome: First Italian Case Treated With Enzyme-Replacement Therapy. Ten Years of Follow-Up

Abstract

The Hunter syndrome (Mucopolysaccharidosis II, MPS II) is a severe genetic disease (X-linked recessive). Its incidence is about 0.3-0.71 per 100 000 live births. It is caused by the deficiency in the lysosomal enzyme iduronate-2-sulphatase (I2S), which catalyses the degradation of the glycosaminoglycans (GAG). This leads to a widespread accumulation of the GAG dermatan and heparan sulphate in many organs with a final progressive multi-system disease. The enzyme-replacement therapy (ERT) with idursulfase, a recombinant human I2S enzyme, is now available (since 2006) in many countries. We described the first case treated in Italy with this method. A 13-month-old male arrived to our Clinic and was diagnosed with MPS II. He was treated with ELAPRASE (0.5 mg/kg intravenously administered every week) since 32 months of age. We monitored the urinary GAG content, the patient’s detailed anthropometric (growth, weight, phenotypic aspects of the face, as well as chest, limbs and whole body), joint range of motion and skeletal radiographs, ultrasound studies of liver and spleen volumes, the distance covered in the 6-minute walk test and respiratory symptoms, echocardiography and heart valvulopathies, otorinolaryngological symptoms, audiological examinations, pain, neurological involvement and psychological tests. The patient was treated for 10 years and he is still in treatment. He now presents i) significant reduction in GAG levels in the biological fluids, ii) important improvements in lung function, in the ability of walking, in other visceral organs function and iii) a significant reduction of the liver and spleen volumes. We can conclude that an early diagnosis is fundamental for an efficient therapy of the Hunter syndrome disease. Indeed the treatment of patients with MPS II before the onset of clinical symptoms may significantly improve the quality of life and the survival. The ELAPRASE treatment is a good option for these patients, but not all patients with MPS II may be elected for this type of treatment. An accurate selection is fundamental also based on high cost of medication.