To explore whether Hap1 depletion in the postnatal hippocampus plays a pivotal role in adulthood depression, we used stereotaxic injection to overexpress c-kit in P3 mouse hippocampus and found that this overexpression can augment hippocampal neurogenesis and mitigate the depressive phenotype caused by the loss of Hap1, further supporting a causal role of reduced postnatal hippocampal neurogenesis in adult depression in our Hap1-deficient mice. Here, HAP1 is linked to depressive disorder.