Evidence · Replicated

What the research found

In the cited research, the C allele at rs3734398 was associated with a lower share of DHA, a long-chain omega-3 fat, among blood fatty acids in the studied cohorts.

TT: Higher average
CT: Middle
CC: Lower average

Slight effect

What the study found

In the study, each copy went with DHA as a share of plasma fatty acids about 0.11 % of total fatty acids lower on average.

European-ancestry adults in five CHARGE cohorts (ARIC, CARDIA, CHS, InCHIANTI, MESA) · 8,866 people · Table 4 (European ancestry, Overall row, DHA columns)

Evidence: Genome-wide meta-analysis across cohorts, supported in other ancestries
Who was studied: European-ancestry adults (CHARGE), with African, Chinese and Hispanic samples

1000 Genomes Project

How common each genotype is

How common each genotype is in the 1000 Genomes Project, by region
Region	TTHigher average	CTMiddle	CCLower average
All regions2,504 people	26%	37%	37%
Africa661 people	57%	37%	7%
The Americas347 people	16%	41%	43%
East Asia504 people	<1%	18%	81%
Europe503 people	33%	48%	19%
South Asia489 people	12%	43%	45%

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	56%33 of 59 copies read
First farmers6500 to 3000 BC	51%392 of 775 copies read
Bronze Age3000 to 1200 BC	49%339 of 693 copies read
Iron Age and Antiquity1200 BC to AD 600	46%428 of 923 copies read
Middle AgesAD 600 to 1500	55%304 of 555 copies read
Today1000 Genomes	43%433 of 1,006 copies

Neanderthal and Denisovan genomes

Altai Neanderthal: No copies
Vindija Neanderthal: No copies
Chagyrskaya Neanderthal: No copies
Denisovan: No copies

Neanderthals and Denisovans carried the other letter, so this letter is younger than our split with them.

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. Damage in old DNA can fake this letter, so it is counted only from samples treated to remove that damage and from high-quality genomes. Ancient genomes from the Allen Ancient DNA Resource (AADR v66): 15,136 people.

rs3734398

The marker

Gene or region: ELOVL2
Marker: rs3734398
Location: Chromosome 6 · GRCh37 10,982,973 · GRCh38 10,982,740
Letters studied: C and T, with C 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: ELOVL2 · rs3734398
Location: Chromosome 6 · GRCh37 10,982,973 · GRCh38 10,982,740
Studied allele: C
Published statistic: Per C (Europeans, N 8,866): DHA -0.114 (SE 0.014), P 2e-15; DPA +0.040 (0.003), P 1e-43; EPA +0.035 (0.005), P 4e-12; ALA 0.0008, P 0.37 (Table 4). Variance: 0.7% of DHA, 2.8% of DPA, 0.4% of EPA (Results). African ancestry: DHA -0.099, P 0.003; DPA +0.041, P 7e-12 (Table 4) (Table 4 (European ancestry, Overall row, DHA columns))
1000 Genomes Project phase 3, people with 0, 1 and 2 copies: All regions 656 / 932 / 916 · Africa 376 / 242 / 43 · The Americas 54 / 144 / 149 · East Asia 1 / 93 / 410 · Europe 165 / 243 / 95 · South Asia 60 / 210 / 219

See this card in the sample report

Limits

What it cannot tell you

Blood DHA follows fish intake closely. The same marker raises the omega-3 fats one step earlier in the pathway.

Genetic loci associated with plasma phospholipid n-3 fatty acids: a meta-analysis of genome-wide association studies from the CHARGE Consortium (Lemaitre et al., 2011)

The same topic

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