CYP21A2 and hereditary pheochromocytoma-paraganglioma: The co-expression patterns of SULT1E1 and CYP17A1, SULT1E1 and CYP21A2, SULT2A1 and CYP17A1, and SULT2A1 and CYP21A2 pairs of genes were found to have noticeable and high correlations (according to Chaddock scale) in pheochromocytoma–paraganglioma.