Journal club: Genetics breaks the relationship between obesity and diabetes

Samoans tend to be physically large people, with a very strong build in addition to being at high risk for obesity. More than 50% of Samoans are obese, one of the highest rates in the world. A recent paper in Nature Genetics mapped this susceptibility to obesity to a mutation in CREBRF (p.Arg475Gln), which is common in Samoans and very rare in the rest of the world. This gene is extremely potent, the strongest obesity-causing polymorphism yet found.

Samoans also have one of the highest rates of type 2 diabetes in the world, so it is very easy to point a finger and assume that CREBRF causes both obesity and diabetes. Intruigingly, this is wrong - CREBRF (p.Arg475Gln) drives obesity but actually protects against diabetes! 

Increasingly, the theoretical correlation between BMI and diabetes seems to be breaking down. China is having both an obesity and diabetes epidemic, with the transition to a Western diet, but in China there is essentially no correlation between BMI and diabetes. It is starting to look as if diet drives these two phenomenons independently, and diabetes is not simply a consequence of obesity.

Read the article: Minster, R.L. et al. 'A thrifty variant in CREBRF strongly influences body mass index in Samoans'. Nature Genetics 48, 1049–1054 (2016).