Further studies that aim to replicate our findings in independent, possibly non-European samples, explore expression of AQP4 in atherosclerosis-relevant tissues as a function of genotype at variant rs528732638, and explore the expression of AQP4 in depressed patients with and without atherosclerosis, and functional studies (e.g., animal models) are the next potential steps to elucidating the role of AQP4 in vascular depression. The gene discussed is AQP4; the disease is atherosclerosis.