From Stanford University School of Medicine:
"Researchers at Stanford and 14 other institutions carried out a study of common DNA variations throughout the genome, and then combined forces with two independent studies to complete a pooled analysis of 27,000 individuals. The largest genetic differences between the study participants with and without schizophrenia were found on a stretch of chromosome 6 containing numerous genes associated with immune response (and some with other roles). This raises the possibility that immune function plays a role in schizophrenia."
See the full story at http://med.stanford.edu/news_releases/2009/july/schizophrenia.html