Genetic analysis of quantitative traits in highly ascertained samples: Total serum IgE in families with asthma

The objective of this study was to compare the effect of an approximate asc ertainment correction using proband phenotypes with heuristic corrections b ased on sample trait means and on published "standard" population values. D ata were from the Collaborative Study on the Genetics of Asthma, which comp rises 225 families ascertained through sib pairs affected with asthma. In v ariance component linkage analysis of IgE no lod scores greater than 3.0 we re observed, either with or without several attempted corrections for ascer tainment, The ascertained nature of the sample may have compromised the pow er to detect linkage to a quantitative trait (IgE) associated with the foca l phenotype (asthma). (C) 2001 Wiley-Liss, Inc.