Only the level of HDL-c was found to be negatively associated with serum NNMT levels in the control group (r = − 0.303; p = 0.014), while no correlation between the HDL-c and NNMT levels (p = 0.887) were found in the BD patient group, which instead showed a negative correlation between metabolic parameters, such as TG, CHO, and apo B levels and serum NNMT levels. This evidence concerns the gene APOB and Behcet disease.