A Gene Therapy Trial to Evaluate the Safety and Efficacy of RP-L201 in Subjects With Leukocyte Adhesion Deficiency-I

Inclusion Criteria: * A confirmed diagnosis of severe LAD-I as demonstrated by flow cytometry indicating CD18 expression on \<2% neutrophils (polymorphonuclear neutrophils \[PMNs\]). (Patients in which CD18+ PMNs are \>2% will be considered eligible with \<2% CD11a or CD11b expressing PMNs and if there is a documented ITGB2 mutation and clinical history consistent with LAD-I (or known family history). * At least one (1) prior significant bacterial or fungal infection (US National Cancer Institute \[NCI\] Common Terminology Criteria for Adverse Events \[CTCAE\], v5.0, Grade ≥2). This criteria is not required for patients with documented family history who meet the above inclusion criteria. * Age ≥3 months. * Considered to be an appropriate candidate for autologous transplantation of HSCs. * A competent custodial parent with legal capacity to execute an Ethics Committee (EC)-approved consent form must be available to participate in the consent process. (Informed assent will be sought from capable patients, in accordance with the directive of the EC and with local requirements.) * Ability to comply with trial procedures including investigational therapy and follow-up evaluations. Exclusion Criteria: * Availability of a medically-eligible human leukocyte antigen (HLA)-identical sibling donor transplant. Patients may not be included in this trial as an alternative to a clinically-indicated and feasible HLA-matched sibling donor HSC transplant. If an HLA-identical sibling is ide…