Interestingly, the levels of IgG1 and IgG3 did not differ in women with LVDD, despite the fact that in general women are more prone to develop autoimmune diseases as compared to men.47, 48 In addition, women are more prone to develop HFpEF, whereas men more often develop HFrEF.31 What is causing this sex difference in the progression of LVDD to HFpEF is still poorly understood. This evidence concerns the gene IGHG3 and autoimmune disease.