“…The FUT1 gene, coded on chromosome 19, is responsible for regulating the production of the H antigen, and the ABO gene, coded on chromosome 9, is responsible for regulating the production of antigens A and B; these antigens are present in the blood (erythrocytes), among other tissues such as bone marrow, placenta, and spleen. If expressed, secretive status, coded by the FUT2 gene, antigens of the ABO blood system can be found in tissues such as the trachea, parotid and salivary glands, gastric and intestinal mucosa, uroepithelial cells (bladder and kidney) and female reproductive tract (vagina, cervix, and ovary) (Cooling, 2015;Pereira & Siebert, 2020;Silva-filho et al, 2020).…”