Even though their genes are exactly the same, epigenetics can lead to differences in gene expression in identical twins. A study published recently in the journal Thyroid describes the epigenetic factors in certain chromosomes that make one twin more at risk for autoimmune thyroid disease.
The participants for the study were a group of 23 identical twins that did not have the same amount of anti-thyroglobulin autoantibodies (TgAb) between them. The researchers from the Osaka University Graduate School of Medicine sought to understand the genetic and epigenetic causes for this difference.
Their hypothesis was that there would be differences in the methylation of CpG sites as these sites regulate gene expression and research has shown them to be a factor in diseases such as type 1 diabetes. After performing their study, they found the CpG sites to indeed be different between the sets of twins.
According to the author, this study helps highlight the challenges in diagnosing metabolic diseases. "Looking at only the genes is not enough. We need to study the genetics and epigenetics to determine the risk," said Associate Professor Mikio Watanabe.
Image: Differences in individual sensitivity to environmental factors can be analyzed using monozygotic twins. Image courtesy of the Center for Twin Research, Osaka University Graduate School of Medicine.