Long-Term Follow-up Protocol

This is a long-term follow-up study for people who previously received a gene therapy made by Krystal Biotech, Inc. in an earlier clinical trial. The study monitors participants for years after their gene therapy treatment to track long-term safety and any delayed effects. You may be eligible if: - You previously received at least one dose of a Krystal Biotech gene therapy in an earlier study - You have completed or discontinued the original parent study - You are willing and able to follow the protocol requirements - You (or your parent/guardian if a minor) have provided informed consent You may NOT be eligible if: - You enroll in a gene therapy trial from a different (non-Krystal Biotech) company during this follow-up period Talk to your doctor to see if this trial is right for you.