FUT2 (secretor status)

rs601338

FUT2 determines secretor status: whether blood group antigens appear on mucosa and in secretions. Carrying the stop variant twice makes a person a non-secretor. This influences susceptibility to certain noroviruses, the vitamin B12 level and the composition of the gut microbiome.

Secretor and non-secretor

FUT2 controls the attachment of certain sugar chains (fucosylation) to mucosal surfaces. The stop variant switches the enzyme off in secretions: antigens that otherwise sit on mucosa are absent. Many noroviruses use exactly these antigens as a docking site, which is why non-secretors are often spared.

Wide-ranging side effects

Secretor status changes which antigens the immune system and gut bacteria encounter. From this follow associations with the vitamin B12 level, microbiome composition and some inflammatory and autoimmune diseases, such as Crohn's disease. The effects are real but vary in strength by trait.

Context

FUT2 is a good example of a single variant having many small effects at once. Genome shows the genotype; the individual associations are documented to differing degrees depending on the question.

What Genome measures. The genotype at rs601338 (W143X). Homozygous A/A means non-secretor, at least one G allele means secretor.

Related topics

rsIDs, microarray and SNP lookupDisease associations

Sources

  1. 1Ferrer-Admetlla et al., 2009 A natural history of FUT2 polymorphism in humans. Molecular Biology and Evolution 26:1993–2003. doi.org/10.1093/molbev/msp108
  2. 2Hazra et al., 2008 Common variants of FUT2 are associated with plasma vitamin B12 levels. Nature Genetics 40:1160–1162. doi.org/10.1038/ng.210