The lectin pathway, of which Ficolin-3 is the most abundant plasma component, has been implicated in RHD by multiple previous studies; Ficolin 3 itself binds to the highly conserved N-acetyl-beta-D-glucosamine (GlcNAc) antigen, the main carbohydrate antigen of the Group A Streptococcus cell wall. Here, FCN3 is linked to rheumatic heart disease.