For the alcohol dependence phenotype an individual was defined as affected by DSM-III-R alcohol dependence and Feighner definite alcoholism. For this phenotype, an affected sibling pair method was used using GENEHUNTER, where only individuals who are affected are analyzed, though unaffected individuals can contribute information regarding IBD sharing. We used the n-1 sib pair method with the proband being matched to all other affected siblings. This strategy was chosen because the proband is generally more severely affected and more likely represents a "true" case.
