The variance components method implemented in SOLAR was then used to calculate multipoint LOD scores across the genome at 1 cM intervals for alcohol dependence diagnoses with and without the clustering criterion. Linkage peaks exceeding a LOD score of 2.2 were reported as yielding suggestive evidence for linkage as described by Lander and Kruglyak (1995). In addition, linkage peaks exceeding a LOD score of 1.0 were reported as regions of interest. While these latter peaks represent weaker evidence for linkage, reporting such findings may aid future studies and meta-analytic reviews. To ensure that identified linkage peaks were not the result of a small subset of pedigrees, homogeneity tests were performed using the HLOD (Goring, 2002) function available in SOLAR. Specifically, this test contrasts a null model in which families belong to a single distribution exhibiting genetic linkage to the tested locus against an alternative model in which families belong to one of two distributions only one of which shows evidence of genetic linkage to the tested locus.
