A team of Chinese researchers has identified a group of genes that may hold the key to the genetic basis of schizophrenia.

Schizophrenia is a psychiatric condition that affects up to 1% of the world's population, with many heritable factors that are passed down through generations.

Symptoms typically appear late in life, with patients experiencing disordered thought and disturbances in cognition and emotion like hallucinations, psychosis, delusions, and apathy. If not treated effectively, it can be debilitating.

The discovery of a genetic screen for schizophrenia could allow people at risk to take precautions against developing it, or learn to cope with symptoms before they get out of hand.

Recently, scientists have been using genome-wide association studies (GWAS) to analyze genetic variations across entire populations. The technology used in GWAS allows the identification of specific genetic markers for many complex human diseases.

In a previous genome-wide study, the Chinese team found that particular polymorphisms (or gene mutations) in the chromosome 6p21-p22.1 were strongly associated with schizophrenia in the Han Chinese population.

This study, published this week in PLOS One under the name "Replication of Association between Schizophrenia and Chromosome 6p21-6p22.1 Polymorphisms in Chinese Han Population," further investigated several single-nucleotide polymorphisms (SNPs) near the previously identified SNPs.

A sample of 902 schizophrenia cases and 1,091 healthy controls, all Chinese Han descendants who lived in the same area of northern China, were recruited for the study from Peking University in Beijing.

The Han are the largest distinct ethnic group in China, comprising almost 92% of the nation's population. Recent studies have shown that current geographic location in China is a generally strong indicator of ancestral origin, suggesting that where someone lives can be a good proxy for genetic matching.

The participants' blood samples were collected and genotyped, with the results correlated to the extent of their schizophrenia diagnoses according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).

Not only did the scientists replicate the findings of the previous genome-wide study - they also found a significant schizophrenia symptom correlation in four additional SNPs.

The SNP regions identified by the study are involved in immune response and central nervous system development, suggesting that malfunctions in these processes can lead to the psychosis that is a distinctive marker of schizophrenia.

These findings match those of other studies in Europe and Japan, which show strong support for choromosome 6p21-p22.1 as a target for schizophrenia research.

With further research on this chromosome, these findings may help scientists figure out how and why genetic factors lead to schizophrenia, and how to effectively screen people's DNA to evaluate risk for schizophrenia development.