Home treatment with enzyme replacement therapy for mucopolysaccharidosis type I is feasible and safe.

OBJECTIVE: Intravenous enzyme replacement therapy (ERT) with recombinant alpha-L-iduronidase may ameliorate the non-neurological symptoms in patients with mucopolysaccharidosis type I (MPS I). Since home-based ERT for Gaucher and Fabry diseases has been reported to be safe and successful, we investigated the feasibility and safety of home therapy in patients with MPS I. SETTING: This two-centre study included 17 ERT-treated MPS I patients between 1 and 35 years of age. A patient was allowed to transfer to home treatment after a minimum period of 6 months of in-hospital administration of ERT and after a self- or home nurse-supported home setting was arranged. RESULTS: Thirteen out of 17 patients transferred to home treatment with a median time to transfer of 13 months (range 7-40 months). Two patients preferred to continue ERT in the hospital, whereas for two other patients the transfer to home was hampered for practical reasons. All patients who received ERT at home were assisted by either a relative or a nurse. In total over 1000 home infusions were performed and no serious complications were observed. Two infusion-associated reactions were observed, both within the first 3 months of in-hospital administration of ERT. All patients except one developed antibodies against the recombinant enzyme, but this was not associated with the development of hypersensitivity reactions. CONCLUSION: ERT for MPS I applied at home is safe and might alleviate the burden of life-long intravenous treatment in these patients.

Cardiac abnormalities in adults with the attenuated form of mucopolysaccharidosis type I.

BACKGROUND: Cardiac involvement in mucopolysaccharidosis type I (MPS I) has been studied primarily in its most severe forms. Cardiac involvement, particularly left ventricular (LV) systolic and diastolic function, in the attenuated form of MPS I is less well known. METHODS: Cardiac function was prospectively investigated in 9 adult patients with the attenuated form of MPS I. All patients underwent 12-lead electrocardiography, 24 h Holter monitoring and two-dimensional echocardiography including tissue Doppler imaging (TDI). Eighteen age- and sex-matched healthy volunteers served as a control group. RESULTS: Aortic, mitral and tricuspid valve thickening was seen in, respectively, 5 (56%), 4 (44%) and 2 (22%) patients. Moderate mitral valve stenosis was seen in 1 patient and moderate aortic stenosis in 2 patients. All patients had mild-to-moderate aortic and mitral valve regurgitation and 6 patients (67%) had mild-to-moderate tricuspid valve regurgitation. Despite normal LV dimensions, ejection fraction and mass index, MPS patients had lower mean systolic mitral annular velocities (6.1 +/- 0.6 vs 9.1 +/- 1.4 cm/s, p < 0.01) compared to normal control subjects. Similarly, mean early diastolic mitral annular velocities were lower in MPS patients (7.8 +/- 0.9 vs 13.3 +/- 3.3 cm/s, p < 0.01). CONCLUSION: MPS I patients with the attenuated phenotype have not only valvular abnormalities but also LV diastolic and systolic abnormalities.