The Collaborative Study on the Genetics of Alcoholism (COGA) is a large, multi-site genetic study to identify susceptibility genes for alcohol dependence and related phenotypes [1]. The COGA data have been analyzed using nonparametric sib-pair methods with the two-point linkage program and multipoint linkage program for affected sib pairs [2]. Linkage signals were revealed on chromosomes 1, 2, 4, and 7.
