For the detection of bacterial CAP in adult patients, SYN4, a protein that mediates the activity of several inflammatory factors and rapidly increases in response to bacterial infection [33], has been reported to have an AUC of only 0.54 (95% CI 0.42–0.65), with a sensitivity of 31.1% and a specificity of 86.1%—values lower than those evidenced for CRP [34]. The gene discussed is CRP; the disease is bacterial infectious disease.