Non secretor

are individuals with inactive secretor gene FUT2 and missing the enzyme fucosyltransferase‑2. This gene is known for presence of blood group antigens (Dotz and Wuhrer 2016). The enzyme is also essential to form fucosylated human milk oligosaccharides. Together with the Lewis blood group gene FUT3, milk composition is regulated and four global milk groups have been identified in 1997 (Thurl et al. 1997).