A study of almost 500 individuals with schizophrenia has revealed 12 genetic variants thought to increase risk for the disease. Writing in Nature Genetics, the researchers, based at Cardiff University, Wales, UK, revealed that one variant, on chromosome 2, held particular significance.
The researchers scanned the genomes of 479 individuals with schizophrenia using microarray-based technology, and the results were then compared to 2937 'normal' controls. Of the 12 SNPs - single 'letter' variants on a gene that were identified, the SNP in gene ZNF804A was found to have the strongest association with the disorder. This function of this gene is not fully understood but it is known to code for a protein with a zinc-finger domain - a domain that allows proteins, in collaboration with a zinc ion, to bind DNA regulating its activity.
Schizophrenia affects 0.4-0.6 per cent of the population and is characterised by paranoid delusions and disordered thoughts and speech often leading to social isolation. In popular culture, schizophrenia is often confused with multiple personality disorder although there is little symptomatic overlap.
The segregation of schizophrenia in families suggests that the disorder has a large genetic component, but initial studies focussed on a 'schizophrenia gene' and progress stalled in the face of the vastly complex nature of the disorder involving possibly hundreds of genes - a similar story can be found in many psychological disorders.
Current research favours a model for schizophrenia risk based on an array of small risk alleles which in isolation have little or no effect but in combination with other small risk alleles accumulate larger risk for the disease. Other factors thought to be contributory towards risk are early environment, neurobiology, psychological and social processes.
After years of scant success, the last 12 months has seen schizophrenia researchers harness technical advances in genomic resolution to uncover a number of genetic markers for the disorder, giving hope to scientists and schizophrenics alike that the cause of this most socially stigmatised of disorders may soon become a little clearer.