Study Links DNA Methylation Patterns to Childhood Asthma

Overview of Asthma

Asthma is defined by chronic inflammation within the airways, resulting in symptoms such as coughing, wheezing, and difficulty breathing. It affects over 300 million individuals globally, significantly contributing to healthcare costs, diminished quality of life for patients and their families, and in severe cases, mortality. Most individuals with asthma begin to exhibit symptoms in early childhood.

Genetic Influences on Asthma

Research indicates that genetic factors account for 50-60% of an individual’s susceptibility to asthma, as demonstrated in twin studies. Previous large-scale genome-wide association studies have identified several genetic alterations linked to childhood asthma. These changes often involve modifications to existing DNA rather than alterations in the DNA sequence itself.

Understanding Epigenetics

Epigenetic changes refer to the body’s ability to regulate gene expression by adding methyl groups—comprising one carbon and three hydrogen molecules—to specific regions of DNA. This regulatory mechanism dictates how genes function without altering the underlying DNA sequence.

Recent Findings on Epigenetic Changes

A recent study published in The Lancet Respiratory Medicine focused on the epigenetic changes associated with childhood asthma, particularly examining the addition of methyl groups to “CpG” sites. CpG sites are specific regions of DNA where a cytosine base (C) is adjacent to a guanine base (G).

Study Methodology and Results

Researchers analyzed 1,548 blood samples from children aged 4 to 8 and identified 27 methylated CpG sites linked to childhood asthma. Further validation was conducted using an additional 3,196 children aged 4 to 16. This analysis confirmed that 14 of the 27 CpG sites were significantly associated with childhood asthma and reached genome-wide significance. Notably, children diagnosed with asthma exhibited lower levels of DNA methylation in their white blood cells compared to their non-asthmatic counterparts.

Significance of the Study

The researchers believe this investigation represents the largest epigenetic study on asthma conducted to date. The findings indicate that reductions in methylation at specific CpG sites occur postnatally and are closely associated with childhood asthma. While the study does not establish a direct causal link between low levels of CpG methylation and asthma development, it suggests that targeting the implicated genes may enhance future treatment options for asthma.

Reference

Xu C-J, Söderhall C, Bustamante M, et al. DNA methylation in childhood asthma: an epigenome-wide meta-analysis. Lancet Respir Med 2018; 6:379-388.