Base Editing (BE4max) for PRNP c.385A>G (p.Met129Val) in Iatrogenic Creutzfeldt-Jakob disease

Base Editing (BE4max) via AAV9 delivery is a rationale-driven therapeutic strategy for Iatrogenic Creutzfeldt-Jakob disease targeting the PRNP c.385A>G (p.Met129Val) variant (Pathogenic, missense variant, 3 prime UTR variant). The editing system (BE4max (cytosine base editor)) converts the pathogenic C to T (or G to A on the target strand), restoring the wild-type codon. Target tissue: CNS. Therapeutic goal: Permanently lower or ablate PRNP expression in CNS (e.g., via base editing or epigenetic silencing at the PRNP locus) to prevent propagation of pathogenic prions and modify the course of iatrogenic Cr. Risk profile: off-target Medium (bystander bases in editing window), delivery complexity Medium, immunogenicity High (AAV pre-existing immunity).

1. Molecular basis: PRNP NM_000311.5(PRNP):c.385A>G (p.Met129Val) is classified as Pathogenic (ClinVar variation ID 13399). Molecular consequence: missense variant, 3 prime UTR variant. Protein change: M129V, D178N. 2. Epidemiology: Iatrogenic Creutzfeldt-Jakob disease (iCJD) is an acquired prion disease caused by medical procedures that transmit infectious prions. Major sources include cadaveric human growth hormone, dura mater grafts, and to a lesser extent contaminated neurosurgical instruments, corneal grafts, and other pit 3. Standard of care: Across guidelines and public health documents, all forms of CJD, including iCJD, are described as invariably fatal with no effective disease-modifying treatment. Management consists of rapid diagnosis, palliative and supportive care, and stringent infection-control measures for neurosurgical instrum 4. Pipeline: The therapeutic pipeline for prion diseases remains early stage. Multiple small-molecule agents (e.g., doxycycline, quinacrine, pentosan polysulfate) have reached Phase II or compassionate-use settings without definitive efficacy [PAPER-12, PAPER-13, PAPER-14, WEB-11]. An antisense oligonucleotide t 5. CBE clinical validation: BE4max (Koblan et al. 2018) is the gold-standard cytosine base editor. Multiple CBE programs are in clinical development for liver and hematologic targets.

1. No published data specifically correcting PRNP c.385A>G (p.Met129Val) with Base Editing (BE4max); strategy is based on general principles and must be validated preclinically.
2. PAM availability and bystander base analysis for the specific genomic context have not been performed. If no canonical NGG PAM positions the target within the editing window, PAM-flexible variants (SpRY) may be needed.
3. Delivery to CNS tissue remains a major translational bottleneck. Current vectors have limited transduction efficiency in these compartments.
4. Long-term durability, off-target genome-wide effects, and immunogenicity in the target patient population require thorough preclinical and clinical evaluation.