The results showed that serum LPC subclasses, PC subclasses, EtherLPC (18:0 and 18:1), EtherPC (38:6 and 42:3 [1]), SM 30:1, and EtherPE (38:5, 38:6 [1], and 40:6) showed a negative correlation with markers of RA activity, such as the ESR, CRP, and DAS28 (Fig. 4c); such correlations were validated using follow-up serum samples from RA patients (detailed results are available at Online Supplemental file 4). The gene discussed is CRP; the disease is rheumatoid arthritis.