A new Northwestern University study has found that low socioeconomic status (SES) is associated with the level of DNA methylation (DNAm) in a large number of genes in the genome. This suggests that a child’s experiences of poverty become embedded in DNAm and have a significant continuing impact on that child’s health and well-being going forward.

DNA methylation is a process by which methyl groups are added to a DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence.  

The report says profiles of DNAm can alter gene expression and have other impacts, “all of which have potential health implications.” For example the report says profiles of DNAm have been associated with heart disease, cancer, depression and mortality risk. The report notes that “Prior research has also linked patterns of DNAm with measures of SES, … However, little if any research investigates the association between SES and DNAm outside of an affluent industrialized context.

“In this study, we investigate whether profiles of DNA methylation in young adulthood are predicted by SES early in development (infancy/childhood), and in early adulthood in the Philippines.”

For purposes of the study, SES was measured early in infancy, childhood and adulthood and was based on composite measures of income, assets and parents’ education. The report says, “Our analysis identified 2,546 sites across 1,537 genes where DNAm differed significantly in association with SES, suggesting that DNAm is an important mechanism through which SES becomes biologically embedded across a large proportion of the genome.”

The report goes on to say, “Socioeconomic status is one of the most powerful determinants of human health, yet the underlying biological mechanisms remain poorly understood. In this article, we document epigenetic signatures of low SES across the genome in a cohort of young adults in the Philippines. We find that persistently low SES, from infancy to young adulthood, predicts DNAm at 2,546 CpG sites in 1,537 annotated genes. The scope of epigenetic marks is commensurate with the large number of biological systems and health outcomes that are impacted by SES … and our findings suggest that DNA methylation may play an important role.

“In other words, poverty leaves a mark on nearly 10% of the genes in the genome,” said Northwestern News in a prepared statement.  

Thomas McDade, a professor at Northwestern University and a lead author of the study, said in a prepared statement, this is significant for two reasons.

“First, we have known for a long time that SES is a powerful determinant of health, but the underlying mechanisms through which our bodies ‘remember’ the experiences of poverty are not known. … Our findings suggest that DNA methylation may play an important role, and the wide scope of the associations between SES and DNAm is consistent with the wide range of biological systems and health outcomes we know to be shaped by SES.”

“Second, experiences over the course of development become embodied in the genome, to literally shape its structure and function.  

 “This pattern highlights a potential mechanism through which poverty can have a lasting impact on a wide range of physiological systems and processes,” he said. 

The report noted that the associations between SES and DNAm found in the study were “substantially larger than previously reported.” The report noted that children living in poverty in the Philippines are much more likely to experience greater disadvantage associated with factors such as nutritional insufficiency and infectious disease. Analyzing the data in this context, the report said, “may provide greater power for detecting epigenetic signatures of socioeconomic variation, and it may point to different patterns of impact associated with more severe forms of disadvantage.”

Follow-up studies are contemplated.  

The study titled, “Genome-wide analysis of DNA methylation in relation to socioeconomic status during development and early adulthood,” was recently published in the American Journal of Physical Anthropology. Seven other people were coauthors: Calen P. Ryan, Meaghan J. Jones,  Morgan K. Hoke, Judith Borja, Gregory E. Miller, Christopher W. Kuzawa and Michael S. Kobor.