Replagal Enzyme Replacement Therapy for Children With Fabry Disease

TKT029 is an open label multi-center study to assess the safety of enzyme replacement
therapy with agalsidase alfa in children with Fabry disease, who have completed 6 months of
agalsidase alfa therapy in study TKT023 (Cohort 1) or are treatment-naïve (Cohort 2) and
meet all inclusion/exclusion criteria of this study. The study will consist of treatment
with agalsidase alfa for 52 weeks, with periodic reassessments by Shire HGT for continuation
beyond the 52 weeks. A decision on the part of the study sponsor to terminate the study may
be made at any time.

Study tests performed during the Baseline visit in TKT023 will serve as the baseline
evaluation for the TKT029 study for patients in Cohort 1 and at Week -1 for patients in
Cohort 2. The subjects will receive 0.2 mg/kg IV agalsidase alfa every other week. A
number of safety assessments will be performed at Week 13, Week 25, and thereafter, every 26
weeks.

The final study visit will follow 30 days after the last study drug infusion for patients
who withdraw early from the study, at which time a final safety evaluation will be
performed. Patients who complete the study will be telephone interviewed 30 days after
their last study infusion for resolution of any outstanding AEs or concomitant medication
changes.