Mapping the Neurovascular Unit Genetic Architecture of Early-Onset Ischemic Stroke: A Single-Cell Causal Framework for Target Discovery and Therapeutic Translation.

backgroundThe global incidence of early-onset ischemic stroke (EOS) is rising, with younger patients showing marked heterogeneity and lacking traditional risk factors, underscoring the role of undiscovered genetic determinants. The neurovascular unit (NVU) is central to cerebral homeostasis, yet whether its functional alterations contribute to ischemic stroke susceptibility remains unclear. Defining the NVU’s genetic architecture is therefore crucial for elucidating pathogenic mechanisms and advancing therapeutic discovery.

methodsWe integrated single-nucleus RNA-seq–based expression quantitative trait loci (eQTL) from healthy brain tissue with GWAS from the EOS Consortium. Mendelian randomization (MR), Bayesian colocalization, and Steiger filtering were applied to infer causal effects of NVU cell-type–specific gene expression on EOS. Cross-ancestry validation and PheWAS were conducted to assess robustness and pleiotropy. For translational insights, in silico drug screening, drug–disease MR, and molecular simulations were performed.

resultsMR analysis identified two NVU-resident genes—CYP4V2 in excitatory neurons and ANXA11 in astrocytes—as significantly associated with EOS. Both showed strong colocalization and consistent directionality, with cross-ancestry validation prioritizing CYP4V2 as a robust candidate. PheWAS revealed no major pleiotropic effects. Evidence from CYP4V2 knockout mice revealed neurological and metabolic abnormalities, supporting its biological relevance to ischemic stroke susceptibility. Combined drug screening, genetic evidence, and molecular stability analyses prioritized methotrexate as the most promising candidate.

conclusionsThis study maps the genetic architecture of NVU cells and highlights their role in EOS susceptibility. We identified CYP4V2 as a causal gene and a pharmacologically tractable target. These findings provide a translational framework linking NVU dysfunction to ischemic stroke risk and inform future precision medicine strategies.