CD40LG gene editing restores functional CD40L expression in X-HIGM patient T cells. (A) GFP (x-axis) and CD40L surface expression (y-axis) or (B) CD40-muIg binding in response to P/I activation from 2 X-HIGM patient donor CD4⁺ T cells (with and without gene editing). Neither patient expressed detectable CD40L protein or bound CD40-muIg prior to gene editing. Edited cells were GFP enriched prior to analysis. (C) HDR editing rates using CD40LG[GFP.CD40L.3′UTR] (blue) and [GFP.CD40L.WPRE] (green) in T cells from 3 separate X-HIGM patients measured by (percentage) GFP⁺ expression on day 5 posttransfection. *CD40LG[GFP.CD40L.3′UTR] editing of X-HIGM donor 1 represents early nonoptimized editing protocol; no data are available for this patient using the optimized editing conditions.