LINKAGE STUDIES ON CHROMOSOME-22 IN FAMILIAL SCHIZOPHRENIA

As part of a systematic search for a major genetic locus for schizophr enia we have examined chromosome 22 using 14 highly polymorphic marker s in 23 disease pedigrees. The markers were distributed at an average distance of 6.6 cM, covering 70-80% of the chromosome, We analyzed the data by the lod score method using five plausible genetic models rang ing from dominant to recessive, after testing the power of our sample under the same genetic parameters. The most positive lod score found w as 1.51 under a recessive model for the marker D22S278, which is insuf ficient to conclude linkage. However, an excess of shared alleles in a ffected siblings (P <.01) was found for both D22S278 and D22S283, For D22S278, the A statistic was equal to the lod score (1.51) and therefo re did not provide additional evidence for linkage allowing for hetero geneity, but the Liang statistic was more significant (P =.002). Our r esults suggest the possibility that the region around D22S278 and D22S 283 contains a gene which contributes to the aetiology of schizophreni a. (C) 1995 Wiley-Liss, Inc.