A Study to Learn About the Safety and Effects of the Study Drug PRX-102 in Children and Adolescents With Fabry Disease

Change from baseline of 12-lead ECG quantitative parameters: ST Segment

Timeframe: Baseline and 12 Months

Incidence of treatment-emergent Anti-Drug Antibodies (ADAs)

Timeframe: Baseline and 12 Months

Incidence of premedication use at each visit and change of infusion premedications from baseline

Timeframe: Baseline and 12 Months

Pharmacokinetics: Time to maximum plasma concentration (tmax)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetic : Area under the plasma concentration-time curve from time 0 to time t (AUC0 t)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetics: Area under the curve from time 0 to 2 weeks (AUC0-2wk)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetics: Area under the curve from time 0 to infinity (AUC0-∞)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetics: Terminal half-life (t1/2)

Timeframe: Baseline, week 2, week 4, week 12, week 26 and week 52]

Pharmacokinetics: Area under the curve over a dosing interval (AUCτ)

Timeframe: Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetics: Observed drug concentration at the end of the dosing interval (Cτ)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetics: Clearance (Cl)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Pharmacokinetics: Volume of distribution (Vz)

Timeframe: Stage I - Baseline, week 2, week 4, week 12, week 26 and week 52; Stage II -Baseline, week 12, week 26 and week 52]

Change in eGFR

Timeframe: Baseline and 12 Months

Change in annualized eGFR slope

Timeframe: Baseline and 12 Months

Change in urine albumin levels

Timeframe: Baseline and 12 Months

Change in urine protein levels

Timeframe: Baseline and 12 Months

Change from baseline in LVMi as assessed by echocardiogram

Timeframe: Baseline and 12 Months

Change from baseline in LVMi as assessed by echocardiogram

Timeframe: Baseline and 12 Months

Change from baseline in LVMi as assessed by echocardiogram

Timeframe: Baseline and 12 Months

Change from baseline in LVMi as assessed by echocardiogram

Timeframe: Baseline and 12 Months

Change from baseline in LVMi as assessed by echocardiogram

Timeframe: Baseline and 12 Months

Incidence of any cardiac arrythmias as assessed by Holter ECG

Timeframe: Baseline and 12 Months

Change in plasma levels of cardiac biomarkers

Timeframe: Baseline and 12 Months

Change in plasma level of Gb3 concentration (nM)

Timeframe: Baseline and 12 Months

Change in plasma level of lyso-Gb3 (nM)

Timeframe: Baseline and 12 Months

Change in urine level of lyso-Gb3 (nM)

Timeframe: Baseline and 12 Months

Incidence of change from baseline in the number of different pain medications

Timeframe: Baseline and 12 Months

Incidence of Fabry Clinical Events

Timeframe: 12 Months

Change from baseline of Mainz Severity Score Index (MSSI) scores

Timeframe: Baseline and 12 Months

Change from baseline of PedsQL-GI (or GSRS for subjects who reaches 18 yrs of age) scores

Timeframe: Baseline and 12 Months

Change from baseline of FPHPQ scores

Timeframe: Baseline and 12 Months

Change from baseline of PedsQL-PPQ (or BPI-SF for subjects who reaches 18 yrs of age) scores

Timeframe: Baseline and 12 Months

Change from baseline of EQ-5D-Y (or EQ-5D-5L for subjects who reaches 18 yrs of age) scores

Timeframe: Baseline and 12 Months