New York, Nov 23 (IANS): In the largest study of its kind, researchers have discovered rare genetic variations linked to schizophrenia, a severe mental disorder that often includes psychotic experiences, such as delusions or hearing voices that are not there.

The Psychiatric Genomics Consortium, an international team led by Jonathan Sebat from the University of California San Diego School of Medicine in the US analysed the genomes of more than 41,000 people.

Their study, published in the journal Nature Genetics, revealed several regions of the genome where mutations increase schizophrenia risk between four- and 60-fold.

These mutations, known as copy number variants, are deletions or duplications of the DNA sequence. 

A copy number variant may affect dozens of genes, or it can disrupt or duplicate a single gene. 

"This type of variation can cause significant alterations to the genome and lead to psychiatric disorders," said Sebat.

Analysing the genomes of 21,094 people with schizophrenia and 20,227 people without schizophrenia, the team of more than 260 researchers found eight locations in the genome with copy number variants associated with schizophrenia risk. 

The researchers also found that these copy number variants occurred more frequently in genes involved in the function of synapses, the connections between brain cells that transmit chemical messages.

"We're confident that applying this same approach to a lot of new data will help us discover additional genomic variations and identify specific genes that play a role in schizophrenia and other psychiatric conditions," Sebat said.