Is ethnic DNA methylation just ancestry?
In 573 GALA II Latinos, shared ancestry explained a median 75.7% of ethnicity-linked methylation variance, but environmental signals (e.g., maternal smoking loci) still contributed.
Source
Differential methylation between ethnic sub-groups reflects the effect of genetic ancestry and environmental exposures
Study at a glance
- Design
- Cross-sectional — EWAS of ethnicity vs DNA methylation in GALA II Latino participants with genetic ancestry estimates
- N
- N=573 · 573 participants with methylation data; 524 with genomic ancestry estimates (Puerto Rican n=220, Mexican n=276)
- Population
- Latino American GALA II participants (mostly Puerto Rican or Mexican origin) with dense genotyping and methylation arrays
- Outcome
- Ethnicity-associated CpG methylation, fraction explained by shared ancestry, and enrichment for environmentally associated loci
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What they did
Measured DNA methylation and genetic ancestry in GALA II Latino participants, mapped ethnicity-associated CpGs, estimated how much shared genomic ancestry explained those differences, and tested enrichment of environmentally associated sites.
What they found
Ethnicity and ancestry associated with 916 and 194 CpGs. Ancestry accounted for a median 75.7% (IQR 45.8–92%) of ethnicity-associated methylation variance. After ancestry adjustment, 314/834 ethnicity sites remained. Ethnicity-associated sites were enriched for prior environmental associations, especially maternal smoking in pregnancy.
The limits
What it doesn't show
Cross-sectional methylation cannot prove which exposures caused residual ethnic differences; GALA II Latinos may not generalize to all populations.
Key terms
- DNA methylation
- Epigenetic CpG mark influenced by genetics and environment.
- GALA II
- Genes-Environment and Admixture in Latino Americans study.
- Genetic ancestry
- Proportion of African, European, and Native American genomic background.
- EWAS
- Epigenome-wide association scan linking traits to CpG sites.
- CpG site
- Cytosine-phosphate-guanine locus where methylation is measured.
Flashcards
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Quiz yourself
GALA II methylation N was:
Common questions
How many participants had methylation data?
573; mostly Puerto Rican (220) or Mexican (276).
How much ethnicity-linked methylation did ancestry explain?
Median 75.7% (IQR 45.8% to 92%).
Did environment still matter?
Yes; remaining variation and enrichment at exposure-associated loci, including maternal smoking.
How many ethnicity sites remained after ancestry adjustment?
314 of 834 (37.8%).
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