Lewis negative

are individuals that have inactive Lewis blood group gene not expressing the enzyme fucosyltransferase‑3. Milk of Le-negative women lacks α1‑3 and α1‑4 fucosylated human milk oligosaccharide isoforms, such as lacto-N-fucopentaose‑II and ‑III (Kunz et al. 2017). Together with the secretor gene, the Lewis blood group gene defines milk groups.