SERPINE1 and obesity due to melanocortin 4 receptor deficiency: PAI‐1 levels are regulated by a number of factors, for example inflammation, obesity, circadian rhythm, and genetic factors.6, 9, 10 Several polymorphisms within the PAI‐1 gene have been described to influence PAI‐1 levels, of which the most studied is the −675 4G/5G polymorphism of the promoter region (rs1799889).