To validate the potential of the serotonin receptor encoded by 5-hydroxytryptamine receptor 2A (HTR2A) cg15692052 DNA methylation as a diagnostic biomarker for rheumatoid arthritis (RA) and its subtypes. MethylTarget^TM targeted region methylation sequencing technology was employed to analyze the DNA methylation levels of HTR2A cg15692052 in RA, health control, ankylosing spondylitis, psoriatic arthritis, gout, systemic lupus erythematosus, dermatomyositis, and primary Sjögren’s syndrome patients within the region of chr13:46898190~chr13:46897976. Machine learning algorithms were used to analyze data. Compared to the HC group, RA patients and four serological subtypes of RA (RF-negative RA, RF/CCP double-positive, RF/CCP double-negative, and CCP-negative RA) exhibited significantly higher levels of HTR2A cg15692052 methylation (p < 0.05). Methylation levels in RA patients and its four serological subtypes were significantly positively correlated with erythrocyte sedimentation rate or C-reactive protein (p < 0.05). HTR2A cg15692052 methylation levels combined with different clinical features can significantly distinguish RA patients with AUCs ranging from 0.672 to 0.757, RF/CCP double-negative patients with AUCs from 0.825 to 0.966, RF/CCP double-positive RA patients with AUCs from 0.714 to 0.846, and RF-negative RA patients with AUCs from 0.928 to 0.932. The HTR2A cg15692052 DNA methylation level can serve as a diagnostic biomarker for RA and its subtypes. Rheumatoid arthritis is a long-term condition that causes pain, swelling, and stiffness in the joints. Getting an early and accurate diagnosis is very important, but some patients do not show typical signs in regular blood tests, making it hard to detect the disease in time. In this study, we looked at whether a specific chemical change in the body – namely, DNA methylation, which can affect how genes work – could help identify people with rheumatoid arthritis more reliably. We focused on one gene in particular, called HTR2A, and compared this chemical change in people with rheumatoid arthritis, healthy individuals, and people with other joint problems. We found that this signal was noticeably different in people with rheumatoid arthritis, even in those who usually go undetected by common tests. These results suggest that checking for such gene-related changes could help doctors find and treat rheumatoid arthritis earlier, especially in patients who might otherwise be missed.

To validate the potential of the serotonin receptor encoded by 5-hydroxytryptamine receptor 2A (HTR2A) cg15692052 DNA methylation as a diagnostic biomarker for rheumatoid arthritis (RA) and its subtypes. MethylTarget^TM targeted region methylation sequencing technology was employed to analyze the DNA methylation levels of HTR2A cg15692052 in RA, health control, ankylosing spondylitis, psoriatic arthritis, gout, systemic lupus erythematosus, dermatomyositis, and primary Sjögren’s syndrome patients within the region of chr13:46898190~chr13:46897976. Machine learning algorithms were used to analyze data. Compared to the HC group, RA patients and four serological subtypes of RA (RF-negative RA, RF/CCP double-positive, RF/CCP double-negative, and CCP-negative RA) exhibited significantly higher levels of HTR2A cg15692052 methylation (p < 0.05). Methylation levels in RA patients and its four serological subtypes were significantly positively correlated with erythrocyte sedimentation rate or C-reactive protein (p < 0.05). HTR2A cg15692052 methylation levels combined with different clinical features can significantly distinguish RA patients with AUCs ranging from 0.672 to 0.757, RF/CCP double-negative patients with AUCs from 0.825 to 0.966, RF/CCP double-positive RA patients with AUCs from 0.714 to 0.846, and RF-negative RA patients with AUCs from 0.928 to 0.932. The HTR2A cg15692052 DNA methylation level can serve as a diagnostic biomarker for RA and its subtypes. Rheumatoid arthritis is a long-term condition that causes pain, swelling, and stiffness in the joints. Getting an early and accurate diagnosis is very important, but some patients do not show typical signs in regular blood tests, making it hard to detect the disease in time. In this study, we looked at whether a specific chemical change in the body – namely, DNA methylation, which can affect how genes work – could help identify people with rheumatoid arthritis more reliably. We focused on one gene in particular, called HTR2A, and compared this chemical change in people with rheumatoid arthritis, healthy individuals, and people with other joint problems. We found that this signal was noticeably different in people with rheumatoid arthritis, even in those who usually go undetected by common tests. These results suggest that checking for such gene-related changes could help doctors find and treat rheumatoid arthritis earlier, especially in patients who might otherwise be missed.