A comprehensive study of the genetic history of Finnish people has helped investigators to identify 26 potentially harmful DNA variations, of which 19 are unique or 20 times more common in Finland. The study, published in Nature this week, was much facilitated by the relatively small and isolated population of Finland. In fact, researchers estimate that they would need to sequence DNA samples of millions of people to draw the same conclusions they drew in this study, where a pool of 20,000 Finnish individuals was used.

Finland: a bottleneck population

The key to making the associations between genetic variants and its possible health hazards lies in the genetic similarity of Finns. Finland’s genetically similar and isolated population results from two major ‘bottlenecks’, events that drastically reduced the size of the population.

The first bottleneck occurred between 2,000 and 4,000 years ago; the vast majority of Finnish people descend from the founding population that settled in the southern and western regions of the country. The second ‘bottleneck’ happened in the 15th and 16th centuries, where internal migrations created geographically isolated sub-populations.

The migratory history of Finland has expanded certain genetic variants and created a set of diseases that are much more common in Finland than in any other European country. Looking at Finland’s well-document health-care database, the scientists could then analyse the genetic variants of patients and see how they might influence their medical history.

Genetic variants and disease predisposition

The DNA changes, or coding variations, identified by the investigators impact the structure and function of proteins and alter people’s predisposition (Finns or not) to cardiovascular and metabolic malfunctions. Some DNA variants are associated with higher cholesterol levels, greater risk of developing diabetes, and changes in height and body weight.

Finland is not the only paradise for genome researchers, though. The investigators, from the Washington University School of Medicine, the University of Michigan, the University of California, and from several Finnish institutes, would like to try out similar analyses on isolated communities such as Sardinia in Italy, Crete in Greece or the Samoan Islands in the South Pacific. For now, the authors hope to “provide a useful starting point for studies aimed at uncovering biological mechanisms and fostering clinical translation”.

Reference:

Locke AE, Steinberg KM, Chiang CWK, Service SK, et al. Exome sequencing of Finnish isolates enhances rare-variant association power. Nature. July 31, 2019.

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