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.