Because of the unique role of pyruvate carboxylase in brain glutamate formation the highly consistent findings of elevated glutamate or glutamate + glutamine levels in bipolar disorder observed by in vivo1H MRS, serum and post-mortem studies can be readily explained by increased pyruvate carboxylase-mediated anaplerosis in brain of patients with bipolar disorders. The gene discussed is PC; the disease is bipolar disorder.