Single-cell RNA sequencing analysis of WT and Lrg1−/− mouse brain tissues after cerebral ischemia‒reperfusion injury revealed that Lrg1 knockout enhances blood‒brain barrier (BBB) by upregulating claudin 11, integrin β5, protocadherin 9, and annexin A2. The gene discussed is LRG1; the disease is Cerebral ischemia.