The role of A1AT in atherosclerosis, obesity and cardiovascular events is well documented [5,49,55,56,57,58,59,60]; however, distinct A1AT haplotypes or other modifying factors may have aggravating or alleviating effects, which may partly explain the conflicting findings of these studies. The gene discussed is SERPINA1; the disease is obesity due to melanocortin 4 receptor deficiency.