Attempt to replicate linkage of chromosomes 13 and 15 to schizophrenia in a large veterans affairs cooperative study sample

Previous studies reported genetic linkage evidence for a schizophrenia gene on chromosomes 13q and 15q. In the initial phase of our genome-wide scan, we examined these chromosomes by genetic linkage analysis using 166 schizophrenia families. The families, assembled from 7 centers by the Department of Veterans Administration Cooperative Study Program, consisted of 392 sampled affected subjects and 216 affected sibling pairs. By DSM-III-R criteria, 360 subjects (91.8%) had a diagnosis of schizophrenia and 32 (8.2%) were classified as schizoaffective disorder, depressed. These families have diverse ethnic back-grounds. The largest single group were northern European American families (n = 62, 37%), and a substantial proportion were African American kindreds (n = 60, 36%). The chromosomes 13 and 15 markers tested were initially spaced at intervals of approximately 10 cM over the entire chromosome and 2-5 cM for the region with the initial peaks. These markers were genotyped and the data analyzed using semi-parametric affected only linkage analysis. We will report results from the initial phase of our genome scan.