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From SNPedia
Magnitude 2.7
Repute Good
Summary Change in metabolism of certain substances
Criteria Gs310/criteria

Glutathione transferase (GSTz1) is the only enzyme known to biotransform DCA (an alternative cancer drug and a drug used in children with certain metabolic disorders). DCA is also found in chlorinated water. GSTz1 also serves as a bifunctional enzyme that catalyzes the penultimate step in tyrosine metabolism.

The effectiveness of the GSTz1 gene in enabling these reactions would change the level of DCA or tyrosine in someone's body.

It has been found that a three haplotype SNP determines the speed of the GSTz1 enzyme.

G94>A (rs3177427) Glu → Lys at position 32;
G124>A (rs7972) Gly → Arg at position 42; and
C245>T (rs1046428) Thr → Met at position 82 in the GSTZ1/MAAI gene

The rs1046428 snp is not on the 23andMe v3 chip. rs10132619, which is a good proxy, can be used in its place.

A promoter polymorphism, SNP-1002G>A (rs7160195), also affects the functioning of the gene.

The EGT haplotype a fast metabolizer of DCA which is used as the criteria for this genoset. It is considered the good form, though in some circumstances such as undergoing DCA treatment this may not be the most preferred haplotype. However, with respect to chlorinated water exposure and high protein diets (tyrosine), fast metabolism should be helpful. Some of the other haplotypes lead to slow metabolism and can lead to too much DCA or other toxic chemicals in the body.

Further, knowing one's genotype could help a health-care provider establish an optimal dosing of DCA during medical treatments. The below articles noted an extreme difference in plasma concentrations of DCA in cancer patients dosed with exactly the same amount of DCA. Age also plays an important role in determining DCA levels.

"Moreover, the GSTz1/MAAI genotype may confer added risk to populations who are chronically exposed to environmental levels of DCA or its precursors and/or to chronic consumption of protein-enriched diets."

[PMID 21642471] [PMID 24297161] [PMID 18096758] [PMID 18647626] [PMID 1683674] [PMID 21642993]