Fabry disease in children and response to enzyme replacement therapy: results from the Fabry Outcome Survey

The Fabry Outcome Survey (FOS) was established to extend the knowledge of the natural history of Fabry disease and to assess the effects of enzyme replacement therapy (ERT) with agalsidase alfa. As of March 2009, 64 boys and 34 girls with Fabry disease had enrolled in the FOS and been treated with agalsidase alfa for at least 6 months. The prevalence of symptoms tended to be reduced after 12 and 24 months of ERT in patients who experienced symptoms at baseline. In the entire population, non-significant decreases in the prevalence of gastrointestinal problems in boys and pain crises in girls were observed after 12-24 months. Kidney function and left ventricular mass indexed to height remained stable. Fifty-eight treatment-related adverse events were reported in 23 patients (21 boys and 2 girls), including 55 infusion reactions. Anti-agalsidase alfa IgG antibodies were found in two boys. No IgE antibodies were reported. This study represents the largest observational study of paediatric Fabry disease patients treated with ERT and indicates continued safety of long-term ERT in children. Continued long-term follow-up is recommended to determine early initiation of ERT, which could potentially slow or prevent the progression of serious morbidities of Fabry disease.