Chu et al. found that AQP4 knockout mice had significantly more severe edema (approximately 30% greater water content in the peri-hematoma region) and worse neurological deficits after ICH than wild-type mice; AQP4 deficiency also led to greater BBB disruption (more Evans Blue leakage) and increased neuronal death in the hemorrhagic brain [25]. This evidence concerns the gene AQP4 and hematoma.