Genetic predisposition: The cause of some labradors' (and people's) increased risk of obesity

In labrador retrievers, a breed of dog known for its voracious eating, researchers have found multiple genes associated with obesity.

In particular, the researchers looked at the DENND1B gene, which altered labradors' hunger cues and made them more likely to binge. They asserted that this gene was also linked to obesity in people.

The findings are described in the March 6 publication of the journal Science article "Canine genome-wide association analysis identifies DENND1B as an obesity gene in dogs and humans." The study was carried out by researchers from the University of Cambridge in England.

The researchers examined DNA samples from 241 British labrador retrievers. They also collected information on the dogs' body fat percentage, the amount of food they asked for, and the degree to which their owners kept a close eye on their diet.

Following the discovery of five genes associated with fat, the researchers looked into whether these genes also contributed to human obesity. They "examined both large population-based studies, and cohorts of patients with severe, early onset obesity where specific genetic alterations are suspected to explain the weight increase," according to a University of Cambridge news release.

What were the findings of the study?

Of the five genes they had discovered as being associated with body mass and obesity in labradors, the researchers discovered that the DENND1B gene was most strongly.

Out of the five genes they had found to be linked to obesity, the researchers discovered that the DENND1B gene was most strongly associated with body mass and obesity in labradors. Dogs with a mutation in this gene had about 8% more body fat than dogs without the mutation.

The DENND1B gene was found to be present in humans as well, and it was associated with higher body mass in these people. In an interview with the BBC, Dr. Eleanor Raffan, a co-author of the study and a researcher in the Department of Physiology, Development and Neuroscience at the University of Cambridge, stated that before this labrador genetics study, "no one imagined that [DENND1B] gene had anything to do with obesity."

To put it simply, the mutation interferes with a brain signalling system that helps control appetite. According to Raffan, "it alters a system that is involved in regulating how hungry we feel and how much energy we burn off, which changes the tendency to acquire weight."

The researchers also found that dog owners who closely monitored their diet and exercise routines prevented their dogs from becoming obese, even if the dogs had a high genetic risk of obesity. However, such dog owners had to work much harder and pay much more attention. Similarly, weight gain is more common in those with a high genetic risk of obesity.

Why is this significant?

The findings show that obesity affects both humans and dogs in ways that go beyond willpower. It is true that some people eat more, but this is a natural tendency rather than something they choose to do. Therefore, obesity is closely associated with a complex interaction between environment and heredity.

In a press release, Raffan said, "Slim dog owners are not ethically better." The same is true for thin people. Unless they actively work to avoid it, people with a high genetic risk of obesity are likely to overeat and put on weight when there is an abundance of food available.