How relevant are these variants? By integrating our screen with All of Us (>600K genomes) and an IEI cohort (>8K pts), we found 100+ carriers enriched for immune disease phenotypes. So the disease could be markedly common than we thought...

Some PIK3R1 variants were less responsive to leniolisib. We identified combo therapies (e.g. leniolisib + mTORi) that restored suppression in both edited cells and patient samples.

We validated screen results and phenotypes using T cells from two APDS patients with variants mapping to structural GOF hotspots flagged by our screen, directly linking screen data to real disease.

Otherwise-healthy T cells engineered these newly identified GOF variants showed hyperactivation, exhaustion & transcriptional changes—mirroring APDS patient cells. Like patients, they also responded to leniolisib, the FDA-approved targeted inhibitor.

But, more importantly the result: reliable recovery of known pathogenic variants, along with dozens of novel GOF variants previously unstudied or classified as VUS

Usually these are tested one at a time... Instead we used CRISPR base editing to engineer thousands of PIK3CD/PIK3R1 variants in primary T cells, and mapped these to pAKT/pS6—a readout used to guide variant classification in real patients.

Thrilled to re-share our tweetorial on Bluesky: now out in @cp-cell.bsky.social (🔗 tinyurl.com/3a55tsky) - we present a framework to accelerate variant classification, diagnosis & treatment of inborn errors of immunity. A dream MD/PhD project, which has already led to the treatment of a patient.