DNA Traits · Nutrition & metabolism

Fatty acid conversion

How much of the blood's fatty acids is arachidonic acid, an omega-6 fat the body makes from linoleic acid.

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Evidence · Replicated

What the research found

In the cited research, the T allele at rs174537 was associated with a lower share of arachidonic acid, and a higher share of its precursor linoleic acid, among blood fatty acids in the studied cohorts.

GG: Higher average
GT: Middle
TT: Lower average

Strong effect

What the study found

In the study, the average arachidonic acid as a share of plasma fatty acids, by genotype:

GGNo copy: 8.72 % of total fatty acids
GTOne copy: 7.39 % of total fatty acids
TTTwo copies: 6.35 % of total fatty acids

Italian adults aged 21 to 102 from the Chianti region (InCHIANTI) · 1,075 people · Table 2 (InCHIANTI columns, arachidonic acid row)

Evidence: Genome-wide association with independent replication
Who was studied: Italian adults (InCHIANTI) with replication in US adults of European ancestry (GOLDN)

1000 Genomes Project

How common each genotype is

How common each genotype is in the 1000 Genomes Project, by region
Region	GGHigher average	GTMiddle	TTLower average
All regions2,504 people	55%	29%	16%
Africa661 people	95%	5%	Not seen
The Americas347 people	19%	44%	37%
East Asia504 people	23%	40%	37%
Europe503 people	44%	43%	13%
South Asia489 people	71%	27%	2%

Among the 2,504 people of the 1000 Genomes Project, in five world regions. These percentages describe groups of people, never anyone’s chance of having a trait.

Ancient genomes

Through time

How often the studied letter was read in ancient people, era by era, in the region chosen.

Region

Through time: Europe
Before farmingbefore 6500 BC	89%90 of 101 copies read
First farmers6500 to 3000 BC	72%747 of 1,033 copies read
Bronze Age3000 to 1200 BC	63%592 of 942 copies read
Iron Age and Antiquity1200 BC to AD 600	45%704 of 1,562 copies read
Middle AgesAD 600 to 1500	45%544 of 1,222 copies read
Today1000 Genomes	35%351 of 1,006 copies

Neanderthal and Denisovan genomes

Altai Neanderthal: 2 copies
Vindija Neanderthal: 2 copies
Chagyrskaya Neanderthal: 2 copies
Denisovan: 2 copies

Neanderthals and Denisovans carried this letter too: it is the older of the two.

For most ancient people only one of their two copies can be read, so these counts are copies read, not people. Close relatives, repeated samples and samples the archive marks as unreliable are left out. Ancient genomes from the Allen Ancient DNA Resource (AADR v66): 15,136 people.

rs174537

The marker

Gene or region: FADS1
Marker: rs174537
Location: Chromosome 11 · GRCh37 61,552,680 · GRCh38 61,785,208
Letters studied: G and T, with T as the studied allele

A DNA Traits report reads this marker in your raw DNA file and shows which of the three genotypes is yours, with how common it is. It counts the copies of the studied allele; it does not measure the trait itself.

Marker: FADS1 · rs174537
Location: Chromosome 11 · GRCh37 61,552,680 · GRCh38 61,785,208
Studied allele: T
Published statistic: Arachidonic acid mean (SD) by genotype G/G 8.72 (1.86), n 569; T/G 7.39 (1.51), n 414; T/T 6.35 (1.36), n 92; P < 0.0001 (Table 2). rs174537 with AA P 5.95e-46, 18.6% of additive variance (Abstract). GOLDN replication, red cell membrane AA 14.06, 13.45, 12.43, P < 0.0001 (Table 2). Linoleic acid 24.27, 25.24, 25.88 in InCHIANTI (Table 2), P 5.58e-7, not genome-wide significant in InCHIANTI (Results) (Table 2 (InCHIANTI columns, arachidonic acid row))
1000 Genomes Project phase 3, people with 0, 1 and 2 copies: All regions 1377 / 737 / 390 · Africa 628 / 33 / 0 · The Americas 67 / 152 / 128 · East Asia 116 / 204 / 184 · Europe 219 / 217 / 67 · South Asia 347 / 131 / 11

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Limits

What it cannot tell you

Measured as a share of all fatty acids in plasma, which diet also shifts. The same marker moves several omega-6 and omega-3 fats at once.

Genome-wide association study of plasma polyunsaturated fatty acids in the InCHIANTI Study (Tanaka et al., 2009)

The same topic

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