Due to the guidelines for gene therapy for vectors which may undergo latency/ reactivation, Krystal Biotech, Inc. has established a Long-Term Follow-up Protocol which will identify and mitigate the long-term risks to the participants receiving their gene therapy products and capture delayed adverse events in participants, annually, for 5-years following the last study visit. Additionally, it will allow the Sponsor to further understand the persistence of the gene therapy products used in their parent treatment protocols.