The genetics of asthma. Mapping genes for complex traits in founder populations.

The advantages of inbred or founder populations for genetic studies were first noted over 30 years ago [1–3], but interest in these populations was renewed as a result of the explosion of molecular biological techniques and the initiation of the Human Genome Project [4,5]. The relatively small number of founders and recent ancestries that are characteristic of these populations facilitate the search for human disease genes and make them particularly amenable to novel analytic strategies. Founder populations have proven useful for mapping genes that underlie Mendelian disorders [e.g. 6– 10] and multigenic disorders that segregate as Mendelian conditions in specific populations [11,12]. Particular features of population history that are unique to these populations (discussed below) have advanced the search for Mendelian conditions and should facilitate the search for genes that influence susceptibility to complex traits. This paper reviews the features of founder populations that make them useful for mapping studies and discusses the analytical challenges that founder populations pose to geneticists mapping complex traits.