Interestingly, the functional prediction results showed a higher abundance of choline dehydrogenase, glycine amidinotransferase, phospholipase A (2), lower abundance of ornithine aminotransferase, and lysophospholipase, in bacteria of the RA group compared with HC group, however, the abundance of these enzymes was the exact opposite in fungi of RA patients. This evidence concerns the gene OAT and rheumatoid arthritis.