Newly Discovered Genetic Variants Could Increase Obesity Risk Six-Fold, Study Suggests

Topline

Two genetic variants are linked to an increased risk of obesity in adults, according to a new study that researchers believe may have revealed a new way the brain plays a role in obesity.

Key Facts

Researchers have discovered variants in the gene BSN (or Bassoon) increase the risk of obesity as much as six times, and variants in the gene APBA1 also increase obesity risk at an “only nominally significant” rate, according to a study published Thursday in Nature Genetics.

These Bassoon gene variants are rare, only affecting one in 6,500 adults.

The researchers also found these rare variants in the Bassoon gene were associated with an increased risk of developing type 2 diabetes and nonalcoholic fatty liver disease.

These variants were not associated with childhood obesity, making them one of the first genes linked to an increased risk of obesity that doesn’t happen until adulthood, according to the study.

The researchers think the Bassoon and APBA1 genes impact obesity because they’re responsible for transmitting signals through brain cells and also contribute to diseases that lead to brain degeneration—like Alzheimer’s and multiple systems atrophy—so they may play a part in those cells damaging as the brain ages, hurting important connections between cells that control the appetite.

The researchers believe this may be a newly discovered biological mechanism for obesity, as previously studied variants decreased appetite regulation by acting through a part of the brain that’s involved in the hunger process called the leptin-melanocortin pathway—which Bassoon and APBA1 aren’t involved in.

Crucial Quote

“These findings give us a new appreciation of the relationship between genetics, neurodevelopment and obesity,” Giles Yeo, study author and program lead at Cambridge University’s Metabolic Research Council, said in a statement.

Big Number

1 billion. That’s how many people worldwide have obesity, according to recent research published in the Lancet. That includes 879 million adults, and 159 million children.

Key Background

A BMI between 25 and 29 is considered overweight, a BMI higher than 30 is obese and one greater than 35 is considered morbidly obese, according to the Centers for Disease Control and Prevention. Obesity is one of the leading causes of preventable death in the U.S., only second to smoking. Having excess weight or being obese increases the risk of death by between 22% and 91%, according to research from the University of Colorado, Boulder. Obesity increases the risk of many serious diseases like type 2 diabetes, stroke, coronary heart disease, sleep apnea, several types of cancers, gallbladder disease and depression and anxiety. Although environmental factors like fast food consumption are the primary contributors to weight gain, genetic variants also play a role, causing about 7% of all severe childhood obesity cases, according to Children’s Hospital of Philadelphia. Some common genetic disorders that lead to childhood obesity include Prader-Willi syndrome—which causes constant food craving and underdeveloped organs—and Down syndrome.