Second Opinion is a vital dose of the week's news in health and medicine from reporter Kelly Crowe and CBC Health.

In 2003 it was a breakthrough — the first evidence of a direct genetic link between stress and depression. The discovery made headlines. Since then, the original paper has been cited more than 4,000 times, with at least 100 research groups following up on that work.

But it wasn't true. That's the blunt conclusion after an international group of scientists pooled their data looking for that celebrated genetic link between serotonin, a neurotransmitter, and stress-related depression.

The original finding suggested that people born with a short variant of a gene for transporting serotonin were at a higher risk of depression if their lives became stressful. It was a tempting hypothesis, that people with the short gene couldn't get serotonin into their brains fast enough when they were exposed to trauma, leaving them more vulnerable to depression.

At Washington University in St. Louis, statistical geneticist Rob Culverhouse rounded up all of the scientists who had researched this hypothesis and convinced most of them to participate in a gigantic group project.

In a series of international conference calls spanning time zones that had some working into the night and others getting up before dawn, the more than 98 scientists wrangled their data into a harmonized form so that they could compare statistical apples to apples.

And then, in a spectacular example of failure to replicate a scientific finding, when they did the final analysis, they couldn't find a link between the serotonin genes, depression and stress.

How did the original scientists get it wrong?

"We think their results reflected their data, but any time you sample something you can get an unusual result," Culverhouse told us. "That's why it's so important to have true replication studies. Findings that are true will be replicated."

Culverhouse expects scientists will one day find a genetic/environmental link with depression. It's just not this one. "There is still a mechanism out there to be found, and we're more likely to find it if we stop looking here."

How many prime ministers does it take to ban trans fats?

Remember how Canada was going to ban trans fats? The long, slow march took another step forward late Friday afternoon when Health Canada released a "Notice of Proposal" detailing its plan to add the main source of trans fats to its "List of Contaminants and Other Adulterating Substances in Foods".

A trans fat ban has proven to be an elusive target for the federal government. In the 1990s, when the first evidence of a health risk emerged, Canadians were among the world's biggest consumers of partially hydrogenated oils. A ban was first proposed by the NDP in 2004. The minority Liberal government struck a task force to study the issue. Later, a Conservative government came out with a two-year deadline calling on industry to comply with voluntary limits, but the deadline came and went.

This time stakeholders have until June 21 to respond to the proposed ban. If passed, it means trans fats will join petroleum jelly and oil-of-Brazilian sassafras as substances that manufacturers are banned from putting in food.

And it means Health Minister Jane Philpott can check off one item from the mandate letter issued to her by Prime Minister Justin Trudeau in November 2015.

The U.S. Food and Drug Administration's prohibition on artificial trans fats comes into effect in 2018.

Not that there's anything wrong with that…

Remember the famous Seinfeld episode called "The Parking Garage" where Jerry is arrested after urinating in a parking garage? The main character in the popular sitcom tried to avoid the charges by telling police he had a disabling fictitious condition known as "uromycitisis." Clearly, the publishers at the Urology & Nephrology Open Access Journal missed that episode.

A Seinfeld lover submitted a fake paper about an imaginary condition the comedian played up on his show. It was published.

When non-scientist and non-urologist John McCool sent them a mock paper about uromycitisis, it was peer reviewed and accepted for publication within a few days, if McCool agreed to pay $799 plus tax. McCool refused to pay, but the paper was published anyway. The paper lists the names of three fictitious authors from a non-existent research institute, all using references drawn from the Seinfeld cast of characters.

McCool, a self-described Seinfeld "fanatic," told us he got the idea for this prank after another journal run by the same publisher MedCrave Group invited him to submit a paper even though he is not a scientist.

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