Secretor Status DNA Test
Impotence of determining secretor status
A Secretor is defined as a person who secretes their blood type antigens into body fluids and secretions like the saliva in your mouth, the mucus in your digestive tract and respiratory cavities, etc. Antigens are molecules capable of inducing an immune response (to produce an antibody) in the host organism.
Secretor also has more stable ecosystem of probiotic (“good”) bacteria in the intestines. Non-secretor has genetic predisposition to be less susceptible to norovirus and rotavirus infection because of the mutations in FUT2 genes. It is thought that these viruses need to bind to ABO blood group antigens in order to infect a person and since non-secretors do not express these antigens in their saliva or gastrointestinal tract, they usually don’t get sick from norovirus and rotavirus. However, there might be some other factors that are related to the norovirus and rotavirus infection. Some publications indicate that some of probiotic bacteria (they also express antigens) which are naturally present in gastrointestinal tract may help norovirus and rotavirus infection (Rodríguez-Díaz J. et. al. Relevance of secretor status genotype and microbiota composition in susceptibility to rotavirus and norovirus infections in humans. Nature, Scientific Reports 7, Article number: 45559 (2017) doi:10.1038/srep45559).
Ratio of Secretors and Non-secretors in the general population is 80% (secretors) and 20% (non-secretors).
Information about the secretor status is also used if following the Blood Type Diet since secretor phenotypes are correlated with the activity of intestinal and serum enzyme alkaline phosphatase.
By following the specific diet plan a person can not only get rid of extra pounds, but also reduce the risk of some diseases that are associated with a particular secretor status. For the Blood Type Diet knowing your secretor status is as important as knowing your blood type
Determining secretor status by the analysis of the FUT2 gene
Pyrosequencing method is used for the analysis of the fucosyltransferase 2 gene.
Understanding the generic risk
Depending on the blood group, red blood cells have different proteins (antigens) on their surface; A, B O. In most people, these antigens are also found on the surface of other cells including those that line the walls of our oral cavity, intestines, and stomach. These antigens are encoded by the fucosyl transferase genes FUT1 (for red blood cells) and FUT2 (for mucous tissue and saliva cells). Mutation in both alleles of the FUT2 gene prevents the expression of antigens on the surface of mucous tissue cells. People who have such a mutation are non-secretors and as such are extremely resistant to most strains of norovirus that causes stomach flu (nausea, vomiting, diarrhea, abdominal pain, general weakness, muscle pain, headache, cough, borderline temperature). Namely, in order for a virus to attack a cell, it needs to bind to it using its antigens (A, B or O), and since non-secretors do not have these antigens on the surface of their cells, the virus cannot attack them.
Figure 1: Red blood cells express antigens on their surface (A, B and / or O, depending on the blood group). Antigens also appear on other cell types (including cells lining the walls of the gut and stomach). People who express antigens on the surface of their cells are secretors, and those who do not (due to a mutation in the FUT2 gene) are non-secretors. (Image accessed from https://personalgenomes.wordpress.com/2012/02/29/invulnerability-to-stomach-flu-is-my-secret-superpower/)
Figure 2: Secretors express their ABO blood group modifications on the surface of gut tissue cells. Norovirus uses these to recognize and enter the cells. As a result, non-secretors (who don’t have these modifications in gut tissue) are extremely resistant to the virus — the virus can’t find the cell, and thus can’t infect it. (Image accessed from https://personalgenomes.wordpress.com/2012/02/29/invulnerability-to-stomach-flu-is-my-secret-superpower/)