RETN and obesity due to melanocortin 4 receptor deficiency: Highly downregulated genes at day 1 included genes associated with obesity including Col6a5 (collagen type VI alpha 5 chain), Fgg (Fibrinogen Gamma Chain), and adipokines Lcn2 (Lipocalin 2) and Retn (resistin) (Fig. 2A)32–34.