Genes for "Good" and "Bad" Fat Come From Different Sides of the Family

Thanks, dad. 

Most inherited characteristics are rooted in a combination of both mom’s and dad’s genes, but sometimes traits can be blamed on just one of your parents. This was illustrated in September, when a study published in Nature Communications showed that “bad” fat genes are inherited from dad.

The study, begins with the important distinction between the two different types of fat and their very different effects. There’s white fat, the “bad” kind that accumulates over time and doesn’t burn many calories at rest. White fat is primarily stored energy for later use. Then, there’s “good” brown fat, which actively burns calories more efficiently and produces heat. Dad, it turns out, only seems to contribute to white fat formation.

This story is #12 on Inverse’s 25 Most Surprising Human Discoveries Made in 2018.

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Genes that favor white fat development tend to come from dad

The study was co-authored by Jan-Wilhelm Kornfeld, Ph.D., a biochemist from the University of Southern Denmark, and Martin Bilban, Ph.D., from the Medical University of Vienna. They discovered that several genes that determine whether fat cells will become white fat or brown fat belong to a unique category called monoallelic genes. Usually, a human embryo gets one copy of a gene (called an allele) from mom and the other from dad. When a gene is monoallelic, only one of those copies ends up being used by the embryo when it’s developing.

When Kornfield and Bilban looked in depth at white fat cells in a population of obese mice, they found only the genes originating from dad’s side were the ones being expressed in those white fat cells.

But fortunately, other genes were able to change the destiny of those white fat cells. In particular, they looked at a gene called H19, which usually isn’t expressed in white fat cells but is very active in brown fat cells. It actually comes from mom’s side of the family.

Kornfield and Bilban genetically manipulated mice to express this maternal copy of H19 in their white fat tissue and found that it had a “beiging” effect on the white fat, causing it to burn energy in a similar way as brown fat. Bilban previously told Inverse that they believe that mom’s h19 tended to act as a gatekeeper, blocking expression of the white fat genes that came from dad’s side.

“This not only prevented the accumulation of white adipose tissue during obesity, more importantly, H19 seems to convert white adipose tissue into so-called‚ beige adipose tissue, which resembles brown adipose tissue in some aspects. e.g. it can convert energy into heat just like brown fat does,” Bilban said.

Even if these findings don’t exactly illuminate an easy way to combat white fat, they do give us an idea of where each type of fat comes from and what we can thank each parent for.

As 2018 winds down, Inverse is highlighting 25 surprising things we learned about humans this year. These stories told us weird stuff about our bodies and brains, uncovered insights into our social lives, and illuminated why we’re such complicated, wonderful, and weird animals. This story was #12. Read the original story here.