[Follow-up of patients with Hunter syndrome: the Hunter Outcome Survey (HOS) registry].

INTRODUCTION: Hunter syndrome, or mucopolysaccharidosis type II, is an inherited disease linked to the X chromosome that is caused by a deficit of the enzyme iduronate-2-sulfatase and its main symptoms affect the bones, neurological system and the viscera. In order to further our knowledge of its natural history, a registry containing data about patients' clinical histories was compiled. The purpose of this review is to describe how the registry works and to present the initial data concerning Spanish patients with Hunter syndrome included in it. DEVELOPMENT: The Hunter Outcome Survey (HOS) registry is a multi-centre, world-wide, observational, long-term follow-up study that is open to all patients diagnosed with the disease. The registry includes clinical data and information from the complementary examinations that are commonly performed as usual practice while attending these patients. Its main aims are to describe the population of patients with the disease, to further our knowledge of its natural history, to keep a check on the safety and effectiveness of enzyme replacement therapy in patients who are candidates for such treatment and to create a database that makes it possible to draw up a set of guidelines for clinical practice.
CONCLUSIONS: Specific registries of low-prevalence diseases, such as the HOS registry for patients with Hunter syndrome, are important to improve the follow-up of patients and to determine the impact of new treatments. The Spanish HOS registry is an important step forward in furthering our knowledge of the current situation of the patients registered throughout the country.