New genetic cause of obesity could help guide treatment

Scientists have discovered a new cause of why people who lack a specific blood group are genetically predisposed to be overweight or obese.

A team of international researchers, led by the University of Exeter, discovered that people with a genetic variant that disables the SMIM1 gene have higher body weight because they expend less energy when at rest.

SMIM1 was only identified 10 years ago, whilst searching for the gene encoding a specific blood group, known as Vel. One in 5,000 people lack both copies of the gene, making them Vel-negative.

The findings from the new research suggest that this group is also more likely to be overweight, a conclusion which could one day lead to new treatments. The study found that people without both copies of the gene have other measures linked to obesity including high levels of fat in the blood, signs of fat tissue dysfunction, increased liver enzymes as well as lower levels of thyroid hormones.

The study, published in Med, was funded by the National Institute for Health and Care Research and the British Heart Foundation. The collaboration included partners at the University of Cambridge, the Sanger Institute, the Copenhagen University in Denmark, and the Lund University in Sweden.

Lead author Mattia Frontini, Associate Professor of Cell Biology at the University of Exeter Medical School, said: “Obesity rates have nearly tripled in the past 50 years, and by 2030, more than one billion individuals worldwide are projected to be obese. The associated diseases and complications create significant economic burden on healthcare systems.

“Obesity is due to an imbalance between energy intake and expenditure, often a complex interplay of lifestyle, environmental, and genetic factors. In a small minority of people, obesity is caused by genetic variants. 

“When this is the case, new treatments can sometimes be found to benefit these people. Our findings highlight the need to investigate the genetic cause of obesity, to select the most appropriate and effective treatment, but also to reduce the social stigma associated to it.”