Chinese scientists identify gene that could help protect against obesity

A 2022 study published in The Lancet ranked Chinese women 190th in the world in terms of obesity prevalence, and Chinese men 149th.

While factors such as diet and developmental levels are obviously important, a recent study led by Professor Jin Li and Associate Professor Zheng Hongxiang of Fudan University suggests that genetics could also be a factor.

The team analyzed 2,877 samples from three independent populations in the southwestern Guangxi region, eastern Jiangsu province and Henan in central China for the study, which was published in the Journal of Genetics and Genomics , peer-reviewed.

She identified a type of mitochondrial DNA known to be prevalent in southern China and Southeast Asia that appears to act as a protective factor against obesity.

“Mitochondria are often considered the powerhouses of cells, generating 80 to 90 percent of the energy needed for various human behaviors. Mitochondrial function has long been associated with obesity,” Jin wrote.

Unlike cell nucleus DNA, which comes from both parents, mitochondrial DNA is usually inherited only from the mother. Compared to nuclear DNA, it is more likely to accumulate genetic mutations, often used in evolutionary analysis.

Jin and colleagues conducted association analyzes of 16 basal mitochondrial DNA haplogroups, genetic families that trace back to a common ancestor.

They found that a specific variant group named M7 was consistently associated with a reduced risk of obesity. Further analysis identified a subgroup named M7b1a1 as the most likely source.

A 2019 study, by Professor Kong Qingpeng of the Chinese Academy of Sciences, published in Molecular Biology and Evolution, found that this specific subgroup “was mainly distributed in southern China and Southeast Asia.” Eastern mainland and had considerable frequencies among Southern Han Chinese individuals – approximately 5 to 14 percent.”

Jin said a decrease in mitochondrial function could be why M7b1a1 reduces the risk of obesity.

“Decreased mitochondrial function represents less energy saving and more heat production, which could lead to less weight gain,” he writes in the article.

The researchers also found that M7b1a1 appears to have undergone a population expansion around 15,000 years ago.

Jin said this further supports their hypothesis, adding: “M7b1a1 carriers with greater heat generation may have adapted well to the cold climate of the Ice Age, which may have been evolutionarily advantageous for positive natural selection.

“Our findings… offer new insights into the genetic basis of obesity-related traits, thereby improving our understanding of how genetics may influence body fat distribution and obesity risk.”