Novel approaches to the analysis of family data in genetic epidemiology

THE IMPORTANCE OF FAMILY DATA The study of Genetic Epidemiology has historically focused on the inheritance of genetic factors and phenotypes within families. In fact, much of genetics involves the study of patterns of familial resemblance and identifying the factors that explain the observed patterns. However, in recent years the most common study design for investigating the genetic determinants of diseases has become that of genome wide association studies (GWAS) utilizing samples of unrelated individuals. The popularity of this approach has been driven primarily by a flood of ever improving technologies. Unfortunately, while GWAS using unrelated individuals have revealed a great many interesting disease associated variants, these variants are typically of small effect and cannot explain the observed patterns of heritability for many traits. In contrast there are numerous examples of highly penetrant rare segregating alleles that have been discovered using family based approaches. Furthermore, family based approaches have other advantages: the ability to overcome confounding factors such as population stratification, and the numerous studies that have collected large amounts of family data and which should continue to be leveraged. Unfortunately, family based approaches to genetics have an added layer of complexity at all stages from design to analysis. This editorial introduces the Frontiers in Genetics Research Topic and Ebook: “Novel approaches to the analysis of family data in genetic epidemiology.” The papers in this issue reveal that, even with easy access to high-throughput genotyping tools such as SNP arrays and next generation sequencing, family based study designs still play an important role in untangling the complex web of environmental and genetic factors that lead to disease.