This Long-Term Follow-Up (LTFU) for Gene Therapy of Leukocyte Adhesion Deficiency-I (LAD-I) is a continuation of a Phase 1/2 clinical study to evaluate the safety and efficacy of the infusion of autologous hematopoietic stem cells transduced with a lentiviral vector encoding the ITGB2 gene

Following the end of participation in Study RP-L201-0318, patients will be offered enrollment into this LTFU protocol. Patients will be followed for up to 15 years following the RP-L201 infusion in the parent study, until the patient dies, withdraws consent, or is lost to follow-up (whichever occurs first).

For all follow-up visits, remote evaluation facilitated by local health care providers (with blood sample shipment to relevant laboratory facilities) is permitted; however, annual visits to the study center are required during initial 3 years post- RP-L201 infusion. Visits where a bone marrow sample is being collected are required to be performed at the study center for the duration of the study. Peripheral Blood samples and bone marrow samples will be archived and tested when clinically or scientifically indicated, as in the event of development of a second malignancy.

Inclusion Criteria:

1. Enrolled in the Phase I/II Study RP-L201-0318.
2. Received an autologous infusion of CD34+ hematopoietic stem cells modified with a lentiviral vector containing the ITGB2 gene, encoding for the human CD18 receptor in the parent Study RP-L201-0318.
3. Able to adhere to the study visit schedule and other protocol requirements.
4. Provided written informed consent and, as applicable, assent to participate in the current study.

Exclusion Criteria:

There are no criteria for exclusion in this study.

Subjects that have been treated with RP-L201 on the RP-L201-0318 study.