Genome screen for platelet monoamine oxidase (MAO) activity

To identify loci involved in the control of platelet monoamine oxidase B (M AO-B) activity, a genomewide linkage screen was performed using 291 markers in 148 nuclear families containing a total of 1,008 nonindependent sib-pai rs, Participants were genotyped and their platelet MAO-B activity levels we re measured as part of the Collaborative Study on the Genetics of Alcoholis m (COGA). Sib-pair analysis using Haseman-Elston regression was carried out with two programs, Two-point analysis on all pairs with SIBPAL indicated t hree markers with p-values below 0.01: D6S1018 (p=0.0004), D2S1328 (p=0.008 ), and D2S408 (p=0.003), MAPMAKER/SIBS multipoint analyses using independen t pairs(N=409) gave maximal lod scores of 2.0 on chromosome 6 and 1.1 and 1 .4 for the two regions on chromosome 2, These results are consistent with l inkage, but do not provide definitive evidence. We are currently creating a denser map in these regions and have begun genotyping a second sample in C OGA, (C) 1999 Wiley-Liss, Inc.