Variants in the FUT2 gene (fucosyltransferase 2) may impact B12 absportion and the production of prebiotics, to support the colonization of probiotics. Genome-wide association studies have recently identified several common single nucleotide polymorphisms (SNPs) in fucosyl transferase 2 gene (FUT2) to be associated with levels of vitamin B12—the strongest association was with a non-synonymous SNP rs602662 in this gene. From various GWAS studies, the SNP in FUT2 gene (rs602662) has been consistently shown to be the most significant SNP associated with levels of vitamin B12.
In a separate study, Hazra et al. carried out GWAS on women of European ancestry and have shown that SNPs in FUT2 gene (rs602662, rs601338 and rs492602) are associated with levels of vitamin B12. Further, a meta-analysis of three GWAS on 4763 individuals of European ancestry revealed that all three SNPs in FUT2 gene are associated with levels of vitamin B12. This SNP is located in exon 2 of the FUT2 gene and it has been reported that the presence of an A allele is associated with a 44.2 pg/ml higher concentration of vitamin B12. Thus, carriers of the A allele will have higher levels of vitamin B12 than the carriers of the G allele.
Vitamin B12 is involved in the formation of red blood cells, DNA synthesis and maintenance of the myelin sheath of the nerve. Deficiency in B12 is associated with several disease conditions like megaloblastic anemia, impaired immune defense, high homocysteine levels, gastrointestinal and neurological disorders. Impaired B12 may also reduce the production of methyl groups, thus resulting in less than optimal histamine clearing.
The FUT2 secretions influence the kind and amount of beneficial bacteria that grow in the digestive tract. The main type affected bifidobacteria, which are probiotics that promote health throughout the entire body – bolstering immunity, managing inflammation, and maintaining a healthy gut flora balance. You are called a non-secretor if you are homozygous for non-functional FUT2, which affects probiotic colonization due to poor prebiotic synthesis.
The FUT2 gene determines if we are vulnerable to:
- Autoimmune disorders like Crohn’s disease (mostly affecting the large intestine), celiac disease (affecting the small intestine), and Type 1 diabetes
- Inflammatory bowel disease
- Urinary tract infections
- Susceptibility to the Noro Virus
- B12 deficiency and some forms of anemia