rs601338 is found on chromosome 19 in the alpha(1,2)-fucosyltransferase FUT2 gene. The wild-type rs601338(G) encodes the "secretor" (Se) allele, while rs601338(A) encodes the "non-secretor" (se) allele.
A study of 115 Swedish adults concluded that rs601338(A;A) homozygotes have genetic immunity to infection by the Norwalk norovirus, a major (and contagious) cause of acute gastroenteritis worldwide among adults. [PMID 12692541] [PMID 16306606] This illness is also known as "cruise ship gastroenteritis."
In some non-Caucasian populations, a different SNP is responsible for non-secretor phenotypes. For example, although the Se allele is absent in Japanese, 15% are non-secretors based on being homozygous for the non-secretor "sej" allele of SNP rs1047781. [PMID 8621666]PMID 19744961] Genome-wide significant predictors of metabolites in the one-carbon metabolism pathway
[PMID 22521342] Extended Analysis of a Genome-Wide Association Study in Primary Sclerosing Cholangitis Detects Multiple Novel Risk Loci.
|Disease||SECRETOR/NONSECRETOR POLYMORPHISM, Norwalk virus infection, Vitamin b12 plasma level quantitative trait locus 1|
|CLNDBN||SECRETOR/NONSECRETOR POLYMORPHISM, Norwalk virus infection, resistance to, Vitamin b12 plasma level quantitative trait locus 1|
|CLNSRC||OMIM Allelic Variant|
|CLNACC||RCV000013808.1, RCV000013809.1, RCV000013810.1|
[PMID 18604267] Novel association of ABO histo-blood group antigen with soluble ICAM-1: results of a genome-wide association study of 6,578 women.
[PMID 18776911] Common variants of FUT2 are associated with plasma vitamin B12 levels.
[PMID 19169360] Histo-blood group gene polymorphisms as potential genetic modifiers of infection and cystic fibrosis lung disease severity.
[PMID 19379518] Development of a fingerprinting panel using medically relevant polymorphisms.
[PMID 19474294] Potential etiologic and functional implications of genome-wide association loci for human diseases and traits.
[PMID 20041166] Common genetic variation and the control of HIV-1 in humans.
[PMID 20565774] Population based allele frequencies of disease associated polymorphisms in the Personalized Medicine Research Project.
[PMID 22025780] FUT2 nonsecretor status links type 1 diabetes susceptibility and resistance to infection.
|qualified_impact||Moderate clinical importance, protective|
|summary||This recessive protective variant confers resistance to norovirus (which causes stomach flu). 20% of Caucasians and Africans are homozygous for this variant and are "non-secretors": they do not express ABO blood type antigens in their saliva or mucosal surfaces. Most strains of norovirus bind to these antigens in the gut, and so this non-secretor status confers almost total resistantance to most types of norovirus. There are notable exceptions, some strains of norovirus bind a different target and are equally infectious for secretors and non-secretors.|
[PMID 23402911] Gastric intrinsic factor deficiency with combined GIF heterozygous mutations and FUT2 secretor variant