Significantly higher mesothelin expression was detected in the effusions from mesotheliomas (mean, 6.99; 95% CI, 5.82–8.40) than those from the non-mesotheliomas (mean, 0.65; 95% CI, 0.55–0.77) (p < 0.001). The gene discussed is MSLN; the disease is mesothelioma.