Family-based genetic risk prediction of multifactorial disease
1 Psychiatric and Neurodevelopmental Genetics Unit, Center for Human Genetic Research, Mass General Hospital, Boston, MA, USA
2 The Stanley Center for Psychiatric Research, The Broad Institute of Harvard and MIT, Cambridge, MA, USA
3 Broad Institute of Harvard and MIT, Cambridge, MA, USA
4 Department of Psychiatry, Harvard Medical School, Boston, MA, USA
Genome Medicine 2010, 2:2 doi:10.1186/gm123Published: 15 January 2010
Genome-wide association studies have detected dozens of variants underlying complex diseases, although it is uncertain how often these discoveries will translate into clinically useful predictors. Here, to improve genetic risk prediction, we consider including phenotypic and genotypic information from related individuals. We develop and evaluate a family-based liability-threshold prediction model and apply it to a simulation of known Crohn's disease risk variants. We show that genotypes of a relative of known phenotype can be informative for an individual's disease risk, over and above the same locus genotyped in the individual. This approach can lead to better-calibrated estimates of disease risk, although the overall benefit for prediction is typically only very modest.