Changes in gene expression that do not involve changes to the underlying DNA sequence are referred to as epigenetics. Environmental factors and lifestyle choices can influence these changes, which may play a role in a variety of health conditions, including obesity. A Washington State University study suggests that a proclivity to gain weight is written into the molecular processes of human cells.
The proof-of-concept study with 22 twins discovered an epigenetic signature in buccal or cheek cells that appeared only in obese twins compared to their thinner siblings. More research could lead to a simple cheek swab test for an obesity biomarker and earlier prevention methods for a condition that affects 50% of U.S. adults, according to the researchers.
“Obesity appears to be more complex than simple consumption of food. Our work indicates there’s a susceptibility for this disease and molecular markers that are changing for it,” said Michael Skinner, a WSU professor of biology and corresponding author of the study published in the journal Epigenetics.
Obesity appears to be more complex than simple consumption of food. Our work indicates there’s a susceptibility for this disease and molecular markers that are changing for it.
Michael Skinner
The study used twins to help eliminate the role of genetics and instead focused on epigenetics, which are molecular processes that exist independently of DNA but influence how genes are expressed. The discovery of the epigenetic signature in cheek cells rather than fat cells suggests that the obesity signature is likely found throughout the human system.
Skinner added that the signature’s systemic nature suggests that something happened early in one twin’s life that triggered obesity susceptibility. It’s also possible that one twin inherited it but not the other.
For this study, Skinner worked with lead author Glen Duncan, director of the Washington State Twin Registry based at WSU, to identify 22 twin pairs, both identical and fraternal, who were discordant for obesity: one sibling had a body mass index of 30 or higher, the standard for obesity defined by the Centers of Disease Control and Prevention, while the other sibling was in the normal range of 25 and below.
Cells from cheek swabs provided by the twins were analyzed by the research team. They discovered similar epigenetic changes to DNA methylation regions in the cells of obese twin siblings, areas where molecular groups made of methane attach to DNA, regulating gene expression or turning genes on or off.
The authors stated that the study would need to be replicated with larger groups of people in order to develop a biomarker test for obesity. Duncan explained that the goal would be to identify people earlier in life before they become obese so that health care providers could help develop interventions such as lifestyle changes, medication, or both.
“Ultimately we would like to have some kind of preventative measure instead of our usual approach which is treatment,” he said. “It’s a simple fact that it’s better to prevent a disease, then try to treat it after you have it.”
