Health researchers are a step closer to understanding and treating obesity now that a new McMaster University study has catalogued 79 potential genetic causes of it.

David Meyre, an associate professor, and Yuvreet Kaur, an undergraduate student at the time, have compiled a list of 79 syndromes associated with obesity.

Previous reviews only assumed the existence of 20 or 30 syndromes, Meyre said. But in poring over seven databases and 161 papers, his team found there were actually 79 syndromes — and catalogued them all.

The overall goal? The better we understand these syndromes — including how many there are — the closer we get to understanding obesity.

It won't help most obese people. These syndromes are "exceptionally rare," likely impacting less than 0.5 per cent of people who are obese, Meyre said.

Yuvreet Kaur is the first author on the study, and started the work in her third year of McMaster's undergraduate biology program. (McMaster University)

They're more common in areas with less genetic diversity, he said. Island nations are an example of this. In one area of Iceland, Meyre said, numerous people can have an obesity-related syndrome and trace it back to the same ancestors.

Still, though, this research helps researchers understand the genes and molecules that factor into obesity in the general population too, Meyre said. And that's a good thing.

In 2014, Statistics Canada data shows, 20.2 per cent of adult Canadians, or 5.3 million people, were obese. That brings an increased risk of complications such as diabetes, heart disease, mental health issues and certain types of cancer.

Of the 79 syndromes, 19 are genetically solved to the point where a lab test can confirm them. Eleven are partially clarified. Twenty-seven are mapped to a chromosomal region.

David Meyre and his team catalogued 79 syndromes that lead to obesity. The syndromes are exceptionally rare though. (McMaster University)

Meyre is particularly pleased with Kaur's work. She is the first author of the study, which appears in the journal Obesity Review. She was in her third year in the Bachelor of Sciences honours biology program when she started the research, Meyre said. She's in medical school now.

"It's not only a great accomplishment to publish a paper, but she published a paper in the best obesity journal in the world," said Meyre, who is a visiting professor from the University of Lorraine. He's in McMaster's department of health research methods, evidence and impact.

In a media release, Kaur said the syndromes are still "individually rare," but "are much more numerous and diverse than anticipated."

samantha.craggs@cbc.ca | @SamCraggsCBC