Low concentrations of 1,25(OH)2D, whether resulting directly from low 25(OH)D3 concentrations or following degradation in response to abnormally high 25(OH)D3 concentrations, could then be speculated to provide insufficient stimulation for vitamin D receptors in the brain, resulting in improper functioning of vitamin D-dependent hormonal processes in the brain that otherwise would prevent mood disorders. The gene discussed is VDR; the disease is mood disorder.