DNA Traits · Appearance

Eye pigmentation (SIK1)

How much pigment the iris holds, from blue towards brown.

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Evidence · Replicated

What the research found

In the cited research, the G allele at rs622330 was associated with darker eye pigmentation.

AA: Lighter range
AG: Middle
GG: Darker range

Slight effect

What the study found

In the study, each copy went with eye colour score from blue to dark brown on a seven step self-rated scale about 0.11 points higher on average.

23andMe research participants of European ancestry · 157,483 people · Table 1, region 49 (rs622330: reference allele G, frequency 0.512, beta 0.111, SE 0.0075, P 3.87e-49)

Evidence: Genome-wide association with confirmation in an independent Asian sample
Who was studied: European ancestry (23andMe research participants), with confirmation in Han Chinese and Indian participants from Singapore

1000 Genomes Project

How common each genotype is

How common each genotype is in the 1000 Genomes Project, by region
Region	AALighter range	AGMiddle	GGDarker range
All regions2,504 people	11%	34%	55%
Africa661 people	2%	15%	83%
The Americas347 people	10%	37%	53%
East Asia504 people	13%	45%	42%
Europe503 people	27%	46%	27%
South Asia489 people	6%	33%	61%

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.

rs622330

The marker

Gene or region: SIK1
Marker: rs622330
Location: Chromosome 21 · GRCh37 44,783,287 · GRCh38 43,363,407
Letters studied: A and G, with G 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: SIK1 · rs622330
Location: Chromosome 21 · GRCh37 44,783,287 · GRCh38 43,363,407
Studied allele: G
Published statistic: beta 0.111 (SE 0.0075) per G allele on the zero to six eye colour scale, P 3.87e-49, n 157,483 (Simcoe 2021 Table 1, region 49); the same SNP was one of five of 44 markers significantly associated with quantitative iris colour in an independent Asian meta-analysis of 1,636 Han Chinese and Indian participants from Singapore, P 1.7e-4 against a Bonferroni threshold of 1.13e-3 (Simcoe 2021 Results and table ST6, the table itself blocked) (Table 1, region 49 (rs622330: reference allele G, frequency 0.512, beta 0.111, SE 0.0075, P 3.87e-49))
1000 Genomes Project phase 3, people with 0, 1 and 2 copies: All regions 275 / 853 / 1376 · Africa 11 / 102 / 548 · The Americas 33 / 130 / 184 · East Asia 63 / 229 / 212 · Europe 138 / 229 / 136 · South Asia 30 / 163 / 296

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Limits

What it cannot tell you

A small effect on a self-rated colour scale, and the gene's part in eye colour was first reported in this study.

Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color (Simcoe et al., 2021)

The same topic

More in Appearance

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