CYP21A2 and diabetic kidney disease: To further evaluate the therapeutic relevance of the four MR-validated druggable genes (HLA-DRB1, HLA-DRB5, NOTCH4, and CYP21A2), we examined their tissue-specific expression profiles using the GTEx and Human Protein Atlas datasets, with a particular focus on tissues implicated in DKD pathophysiology, such as the kidney, adrenal gland, immune system, and vasculature.