Genome scans for genetic predisposition to alcoholism by use of transmission disequilibrium test analyses

We report the results of the analysis of three measures of alcoholism and six associated symptoms using transmission disequilibrium (TDT) analysis on data from the Collaborative Study on the Genetics of Alcoholism data set. Implementation of identity-by-state (IBS) routines for error checking revealed 10 reported full siblings that were rejected as a full sibling to all of their purported full siblings with p < 0.05. TDT analysis revealed two loci with significant transmission disequilibrium ( 0.001p < ) on chromosome 1s and 7. Analysis by parental origin found alleles at three loci displaying significant disequilibrium in the transmission o thfe paternal alleles for at least three of the nine tested traits. These loci are on chromosomes 6,9, and 13. Analyses of Caucasian families alone and the use of a single affected individual from each family also yielded significant results for the loci on chromosomes 6, 9, and 13. ® 1999 Wiley-Liss, Inc. Key words: HTR-2A, identity-by-state, linkage, linkage disequilibrium