Indeed, several polymorphisms of genes of the complement system are associated with leprosy: mannose-binding lectin (MBL2), ficolins (FCN1, FCN2 and FCN3), the serine protease associated with them (MASP2—mannose-binding lectin serine protease 2) and complement receptor 1 (CR1, also known as CD35) [10,20–24]. This evidence concerns the gene CR1 and leprosy.