Schizophrenias genetic skyline rising as genetic code linked to illness grows

The largest genomic dragnet of any psychiatric disorder to date has unmasked 108 chromosomal sites harboring inherited variations in the genetic code linked to schizophrenia, 83 of which had not been previously reported. By contrast, the "skyline" of such suspect variants associated with the disorder contained only 5 significant peaks in 2011. 

By combining data from all available schizophrenia genetic samples, researchers supported by the National Institutes of Health powered the search for clues to the molecular basis of the disorder to a new level.

The newfound genomic signals are not simply random sites of variation, say the researchers. They converge around pathways underlying the workings of processes involved in the disorder, such as communication between brain cells, learning and memory, cellular ion channels, immune function and a key medication target.

The Schizophrenia Working Group of the Psychiatric Genomic Consortium (PGC) report on their genome-wide analysis of nearly 37,000 cases and more than 113,000 controls in the journal Nature. The NIMH-supported PGC represents more than 500 investigators at more than 80 research institutions in 25 countries.

Prior to the new study, schizophrenia genome-wide studies had identified only about 30 common gene variants associated with the disorder. Sample sizes in these studies were individually too small to detect many of the subtle effects on risk exerted by such widely shared versions of genes. The PGC investigators sought to maximize statistical power by re-analyzing not just published results, but all available raw data, published and unpublished. Their findings of 108 illness-associated genomic locations were winnowed from an initial pool of about 9.5 million variants.