29 March,2011 01:56 PM IST | | IANS
Just like snowflakes, no two people are alike, even if they're identical twins, a study suggests.
Molecular geneticist Shiva Singh from the University of Western Ontario, Canada, looked at about one million markers of identical twins (and parents) where only one twin had schizophrenia.
"The most informative feature of schizophrenia is that it sometimes runs in the family," said Singh, according to the journal Public Library of Science ONE.
"So, for example, the risk of developing schizophrenia is much higher if your brother, sister, mother or father have the disease," says Singh, noting that in the general population, about one percent have schizophrenia.
"We started with the belief that monozygotic (identical) twins are genetically identical, so if one member of identical twins has schizophrenia, then the risk for the other twin should be 100 percent, if it's all due to genes," he added, according to a Western Ontario statement.
"However, studies over the years have shown that the risk of the disease in both twins is only 50 percent," he said.
That means either the twins are genetically not identical or the familial disease involves non-genetic (random) effects.
Singh and his team have now demonstrated that the monozygotic twins are not genetically identical.
He has been working with psychiatrist Richard O'Reilly to determine the genetic sequencing of schizophrenia using identical or monozygotic twins.
