Department of Medicine, University of California, San Francisco, United States; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, United States; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, United States
Department of Medicine, University of California, San Francisco, United States; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, United States; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, United States
Dara Torgerson
Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, United States
Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain; CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
Department of Medicine, University of California, San Francisco, United States; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, United States
Noah Zaitlen
Department of Medicine, University of California, San Francisco, United States
Populations are often divided categorically into distinct racial/ethnic groups based on social rather than biological constructs. Genetic ancestry has been suggested as an alternative to this categorization. Herein, we typed over 450,000 CpG sites in whole blood of 573 individuals of diverse Hispanic origin who also had high-density genotype data. We found that both self-identified ethnicity and genetically determined ancestry were each significantly associated with methylation levels at 916 and 194 CpGs, respectively, and that shared genomic ancestry accounted for a median of 75.7% (IQR 45.8% to 92%) of the variance in methylation associated with ethnicity. There was a significant enrichment (p=4.2×10-64) of ethnicity-associated sites amongst loci previously associated environmental exposures, particularly maternal smoking during pregnancy. We conclude that differential methylation between ethnic groups is partially explained by the shared genetic ancestry but that environmental factors not captured by ancestry significantly contribute to variation in methylation.
