Analysis of epistasis in linked regions in the Irish Study of High-DensitySchizophrenia Families

Epistasis may be important in the etiology of schizophrenia. Analysis of ep istasis has been important in the positional cloning of a gene involved in the etiology of type II diabetes mellitus. We investigated the importance o f epistasis among sis linked regions in 268 multiplex pedigrees in the Iris h Study of High-Density Schizophrenia Families (ISHDSF) by computing pairwi se correlations between nonparametric linkage scores for narrow, intermedia te, and bread diagnostic definitions. The linked regions mere on chromosome s 2, 4, 5, 6, 8, and 10. No correlation reached our a priori level of stati stical significance. Using this statistical approach, we did not find evide nce of important epistatic effects among these sis regions in the ISHDSF. ( C) 2001 Wiley-Liss, Inc.