The search for the psychosis gene

Since psychosis occurs across widely differing social and climatic regions without great variation in incidence or type, it is thought to have a genetic link which is relatively independent of environmental factors. If so, then progress in our understanding of psychosis will only occur when a ''psychosis gene'' is found. A commonly used genetic research strategy is linkage analysis. Linkage refers to the tendency of alleles (genetic variations) to be inherited together. Two alleles placed closely together on a chromosome are more likely to be inherited together than are two alleles which are set further apart. This knowledge allows genetic variations to serve as linked markers for other genes when their existence and location have been tagged. Once the linkage between a disease and a marker locus becomes well established, the linkage defines specific genetic disorders that can be mapped to a well understood region of the human chromosome. This information can then be used to predict disease susceptibility. Another research approach is to use what knowledge we have about the disease process to identify a possible or candidate gene. Both strategies should proceed in parallel. Recent diagnostic advances have led to the emergence of a candidate gene which determines brain symmetry (brain changes in schizophrenia and related psychoses have been shown to be asymmetrical). It is hoped that linkage strategies in concert with continuing work in identifying candidate genes will eventually provide clues to the location of a psychosis gene. (Consumer Summary produced by Reliance Medical Information, Inc.)