Gene therapy approaches for inborn errors of immunity: from bench to bedside

INTRODUCTION: Inborn errors of immunity (IEI) are rare genetic defects that disrupt immune function, often resulting in life-threatening infections, malignancies, and immune dysregulation. Allogeneic hematopoietic stem cell transplantation (HSCT), a curative option for some diagnoses, is limited by donor availability and risks of graft-versus-host disease. This review explores the 30-year evolution of autologous gene therapy as a vital alternative to allogeneic hematopoietic stem cell transplantation for IEIs. AREAS COVERED: Literature search using PubMed for gene therapy for IEI in the last 20 years. We trace the transition from early gamma-retroviral gene addition - which successfully restored immunity in severe combined immunodeficiency (SCID) but carried high risks of insertional mutagenesis and leukemogenesis - to the adoption of safer self-inactivating lentiviral vectors. The field is rapidly advancing beyond viral gene addition toward highly precise gene editing technologies, including CRISPR/Cas9, and base/prime editing, which offer targeted correction with minimized genotoxicity. EXPERT OPINION: Recent milestones in diseases like Wiskott-Aldrich syndrome (WAS) and chronic granulomatous disease (CGD) highlight enormous scientific success, yet significant barriers to accessibility, manufacturing, and affordability remain. Overcoming this requires innovative regulatory frameworks and collaborative funding models. Streamlining development and ensuring equitable access are essential next steps to establishing gene therapy as a safe alternative.