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Double Espresso, Please

In a paper in Scientific Reports, a team of Italian researchers delves into the genetic underpinnings of some people's coffee habits.

The University of Trieste's Paolo Gasparini and his colleagues performed a genome-wide association study of two isolated Italian populations: a cohort of 370 people from a small village in Puglia and 843 people from six villages in the Friuli Venezia region. The researchers genotyped these discovery populations and gauged their coffee consumption through field observations. They uncovered 21 SNPs associated with coffee consumption under a recessive model. The top hit, rs6568479, was linked to an increased consumption of 1.2 cups per day in homozygous carriers.

In a separate cohort of 1,731 people from the Erasmus Rucphen Family study, the researchers replicated five of those SNPs, after controlling for overall increased coffee drinking in that population. The association was weaker, though, which the researchers say could be linked to the different ways of preparing coffee in Italy versus the Netherlands.

All these SNPs fell in the non-coding regions of the PDSS2 gene, which encodes coenzyme Q10. The researchers note that PDSS2 knockout mice have increased expression of genes involved in the caffeine metabolism pathway. They hypothesize that increased PDSS2 expression could inhibit the expression of genes in the caffeine metabolism pathway to prevent the breakdown of caffeine.

"Coffee is protective against some types of cancers, cardiovascular diseases and Parkinson's," first author Nicola Pirastu from Trieste and the University of Edinburgh tells the Guardian. "Understanding what is driving its consumption may help us understand what the effects on these diseases are, and so open new lines of research."