CYB5A and rheumatoid arthritis: Therefore, metabolite ratios were calculated: 17α-hydroxy-pregnenolone/7α-hydroxy-DHEA, 17α-hydroxy-pregnenolone/17,20-lyase (that is, the sum of all C19-steroids produced), and 17α-hydroxylase (that is, 17α-hydroxy-pregnenolone plus 17α-hydroxy-progesterone)/17,20-lyase, were significantly decreased (P = 0.006, P = 0.022, and P = 0.03, respectively) in synovial fibroblasts from RA patients with the rs1790834 A-allele (Figure 3C-E), clearly indicating an effect of the CYB5A genotype on steroid 17,20-lyase activity.