MAOA

Protein:

Monoamine Oxidase A

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Monoamine Oxidase A (MAO-A) is an enzyme which is encoded by the MAOA gene. MAO-A breaks down neurotransmitters such as noradrenaline, adrenaline, serotonin and dopamine, and as such, plays an important role in regulating mood. Located on the X chromosome, women can be heterozygous or homozygous for MAOA (as women have two X chromosomes), whereas men only carry one copy (as they have one X and one Y sex chromosome) and are therefore hemizygous. It is commonly referred to as the “warrior gene” as certain polymorphisms have been linked to an increased risk of violence and aggression, however the exact contribution of MAO-A is likely to be low and the area remains controversial.

See also: The warrior gene: 5 common myths debunked

The MAOA gene is interesting, as changes in its activity don’t relate to individual SNPs, rather they are driven by changes in its promoter region. All genes have a promoter region, which sit upstream of the gene in the DNA sequence and this is the location where polymerase proteins bind and begin to read through the gene.

Within the promoter of MAOA is a region of DNA known as a variable number tandem repeat or VNTR. VNTRs are small sequences of DNA which can be repeated a variety of times, which gives rise to the 2R or 3R terminology you may have seen around MAOA. 2R means that there are two repeat sequences in the VNTR, 3R three repeat sequences and so on. This is important as the number of repeats has a big impact on how well MAOA is “read” by the polymerase protein. When the gene is not read as efficiently not as much MAO-A is produced meaning the breakdown of neurotransmitters is also reduced. It is this lack of MAO-A enzyme activity which is thought to lead to increased aggressive behavior 13.

The 2R, 3R and 5R variants of MAOA show reduced MAO-A enzyme activity have been linked with increased aggressiveness in a variety of studies. However, MAOA variation alone form does not mean that someone will be aggressive, there are numerous other factors associated, with the most important thought to be early life abuse 46.

Whilst proper understanding of MAO-A activity requires complete genetic screening there are several SNPs which associate with MAO-A repeat number; rs1137070 or T1410C, rs3027399 or G1052+680C, rs909525 or C306+527T and rs6323 or G891T.

T1410C

Science Grade
B-
Brain Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%) Major Amino Acid Minor Amino Acid
rs1137070 c t 37AspAsp

Risk Description

As is discussed above it is not possible to completely understand MAOAactivity without genetic screening, which is not available to most consumers. However, the risk ‘T’ allele of T1410C does display a weak association with the 3R form of MAO-A. Therefore, those carrying the risk ‘T’ allele are at risk of displaying increased aggression, particularly when associated with other lifestyle traits 8,9.

Direct Nutrients:*

IngredientActive IngredientEffect
Vitamin B2 Riboflavin phosphate

Vitamin B2 is a cofactor for MAO-A, required for it to function correctly 10. The risk ‘T’ allele of T1410C displays a weak association with the 3R, reduced activity, form of MAO-A; therefore carriers may benefit from vitamin B2 supplementation 11.

Discuss this information with your doctor before taking any course of action.

G1052+680C

Science Grade
C+
Brain Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%)
rs3027399 g c 48

Risk Description

The risk ‘G’ allele of G1052+680C is associated with the 5R form of MAO-A which displays reduced activity. Therefore carriers are at risk of exhibiting increased aggression depending on other life factors  8,9.

Direct Nutrients:*

IngredientActive IngredientEffect
Vitamin B2 Riboflavin phosphate

Vitamin B2 is a cofactor for MAO-A, required for its proper function 10. The risk ‘G’ allele of G1052+680C is associated with the 5R, reduced activity, form of MAO-A; carriers of the ‘G’ allele may benefit from vitamin B2 supplementation 11.

Discuss this information with your doctor before taking any course of action.

G891T

Science Grade
B-
Brain Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%) Major Amino Acid Minor Amino Acid
rs6323 t g 35ArgArg

Risk Description

As discussed above a full understanding of MAOA status requires a complete genetic screen which is not available to most consumers. However, the risk ‘T’ allele of G891T is associated with the 5R form of MAO-A and therefore reduced activity, with the associated risk of aggression, although the link is rather weak 6,7.

Interestingly, the higher activity forms of MAO-A associated with the ‘G’ allele of G891T has been associated with depression, potentially due to more rapid degradation of neurotransmitters although results are conflicting, suggesting this aspect requires further research 8,9.

Direct Nutrients:*

IngredientActive IngredientEffect
Vitamin B2 Riboflavin phosphate

MAO-A uses vitamin B2 as a cofactor in order to function correctly 10. The risk ‘T’ allele of G891T is associated with the 5R, reduced activity, form of MAO-A; therefore carriers of the ‘T’ allele may benefit from vitamin B2 supplementation 11.

Discuss this information with your doctor before taking any course of action.

C306+527T

Science Grade
C+
Brain Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%)
rs909525 t c 28

Risk Description

A full understanding of MAOA status requires a complete genetic screen which is not available to most consumers. However, the risk ‘C’ allele of C306+527T is associated with the 3R and 5R variants of MAO-A which display reduced activity, thereby increasing the risk of aggression in association with other factors 6,7.

Direct Nutrients:*

IngredientActive IngredientEffect
Vitamin B2 Riboflavin phosphate

Vitamin B2 is a cofactor for MAO-A, required for it to function properly 10. The risk ‘C’ allele of C306+527T is associated with both the 3R and 5R, reduced activity, forms of MAO-A; therefore vitamin B2 supplementation may benefit carriers of the ‘C’ allele 11.

Discuss this information with your doctor before taking any course of action.

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