This **study** is for kids aged **2 to <12 years old** with a condition called **Fabry disease**, which is a genetic disorder affecting the body's ability to break down a specific type of fat. The study will test a drug called **migalastat** to see if it is safe and effective for these children. The study will last **12 months** and has two stages: Stage 1 lasts about **3 months**, and Stage 2 lasts **9 months**. After completion, there is an **open-label extension** where participants might continue the treatment. The study involves taking **blood samples** at different times to check how the body absorbs and responds to the drug. Participants should not have used other specific treatments for at least **14 days** before starting. - **12-month commitment**: The study has a total duration of 12 months. - **Multiple visits**: Blood samples will be collected at specific times. - **Safety checks**: Includes a 30-day follow-up if treatment is stopped. Children with certain health issues or who have used certain medications recently may not be eligible. Parents or guardians must consent, and children might need to agree if old enough. Participants will help researchers learn more about treating Fabry disease in young patients.