It has been reported that cancer patients with CD4 lymphopenia have an increased risk of severe toxicity after administration of cytotoxic chemotherapy and CD4 lymphopenia can indicate the worse immune condition and identify the end‐of‐life metastatic in cancer patients.36 Thus, AMPKα2 deficient mice may exhibit the worse immune conditions, compared to the control mice. The gene discussed is PRKAA2; the disease is lymphopenia.