Abstract
Objective: The present study investigated a new set of families of Latin American ancestry in order to detect the location of genes predisposing to schizophrenia and related psychotic disorders. Method: A genome-wide scan was performed for 175 newly recruited families with at least two siblings suffering from a psychotic disorder. Best-estimate consensus procedures were used to arrive at diagnoses, and nonparametric allele-sharing statistics were calculated to detect linkage. Results: Genome-wide significant evidence for linkage for the phenotype of DSM-IV schizophrenia or schizoaffective disorder was found in a region on chromosome 17q21 (lod score, 3.33). A region on chromosome 15q22-23 showed suggestive evidence of linkage with this same phenotype (lod score, 2.11). Analyses using a broader model (any psychosis) yielded evidence of suggestive linkage for the 17q21 region only, and no region achieved genome-wide significance of linkage. Conclusions: The new set of 175 families of Mexican and Central American ancestry delineates two new loci likely to harbor predisposition genes for schizophrenia and schizoaffective disorder. The region with the strongest support for linkage in this sample, 17q21, has been implicated in meta-analyses of schizophrenia genome screens, but the authors found no previous reports of it as a locus for schizophrenia in specific population- or family-based studies, and it may represent the location of a schizophrenia predisposition gene (or genes) of special relevance in Mexican and Central American populations.
