Pharmaceutical target discovery using Guilt-by-Association: schizophrenia and Parkinson's disease genes.

We wish to identify genes associated with disease. To do so, we look for novel genes whose expression patterns mimic those of known disease-associated genes, a method we call Guilt-by-Association (GBA). GBA uses a combinatoric measure of association that provides superior results to those from correlation measures used in previous expression analyses. Using GBA, we have examined the expression of 40,000 human genes in 522 cDNA libraries, and have identified several hundred genes associated with known cancer, inflammation, steroid-synthesis, insulin-synthesis, neurotransmitter processing, matrix remodeling and other disease genes. The majority of the genes thus discovered show no significant sequence similarity to known genes, and thus could not have been identified by homology searches. We present here an example of the discovery of five genes associated with schizophrenia and Parkinson's disease. Of the 40,000 most-abundant human genes, these five genes are the most closely linked to the known disease genes, and thus are prime targets for pharmaceutical intervention.