Lentiviral RAG2 addition for c.293del (p.Thr98fs) SCID

For RAG2 c.293del (p.Thr98fs), lentiviral gene addition to autologous hematopoietic stem cells is the most clinically mature variant-specific approach because early preclinical and clinical data show that restoring functional RAG2 cDNA rescues T/B development without needing allele-specific editing.

Historically, lentiviral vectors encoding codon-optimized RAG2 (RAG2co) corrected Rag2−/− mice, restoring lymphocyte subsets and humoral responses (Blood 2012; PMID:22692499; PMC3464632). Recent reviews summarize that GMP-grade RAG2 lentiviral platforms are entering first-in-human trials and that CRISPR-based insertion of codon-optimized RAG2 is also active in HSPCs (Blood Adv 2024; PMID:40829114; PMC10367010). Observations across these models and vectors align with the MB-110 program for RAG1 SCID, which already treats RAG1-deficient infants with LV-RAG1 CD34+ cells (Mustang Bio press release 2022) and demonstrates durable immune reconstitution, supporting that the same platform logic applies for RAG2 null alleles.

Almost all human experience is still in early-phase or preclinical stages; comprehensive safety, conditioning optimization, and long-term surveillance for integration-related events remain under study. The variant c.293del merely defines diagnosis; clinical benefit depends on early detection, conditioning quality, and infection control because irreversible neurologic damage can arise before gene correction. This argument is therefore mechanistically strong but requires the usual gene-therapy translational safeguards before regarded as proven clinical efficacy for this allele.