Rodgers (Rg) and Chido (Ch) are blood-group antigens and they determine the fourthcomponentof human complement C4. Rodgers and Chido are associated with two C4isotypes (C4A and C4B). In addition to genotype determination. study on expression ofRg and Chido could be useful in disease studies. https://www.parisnaturalfoodes.shop/product-category/vitamin-d3-cream/