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Eur J Epidemiol. 2019 Nov;34(11):987-992. doi: 10.1007/s10654-019-00573-8. Epub 2019 Oct 22.

Commonly used estimates of the genetic contribution to disease are subject to the same fallacies as bad luck estimates.

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Division of Occupational and Environmental Medicine, Lund University, Box 117, 221 00, Lund, Sweden.
Clinical Studies Sweden, Forum South, Skåne University Hospital, Lund, Sweden.
Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Center for Occupational and Environmental Medicine, Stockholm County Council, Stockholm, Sweden.


The scientific debate following the initial formulation of the "bad luck" hypothesis in cancer development highlighted how measures based on analysis of variance are inappropriately used for risk communication. The notion of "explained" variance is not only used to quantify randomness, but also to quantify genetic and environmental contribution to disease in heritability coefficients. In this paper, we demonstrate why such quantifications are generally as problematic as bad luck estimates. We stress the differences in calculation and interpretation between the heritability coefficient and the population attributable fraction, the estimated fraction of all disease events that would not occur if an intervention could successfully prevent the excess genetic risk. We recommend using the population attributable fraction when communicating results regarding the genetic contribution to disease, as this measure is both more relevant from a public health perspective and easier to understand.


Epidemiology; Etiologic fraction; Genetic studies; Public health

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