Washington: Researchers have developed a way that may allow doctors to predict whether children with a genetic disorder will develop autism or psychosis.
Researchers have known that children who are missing about 60 genes on a certain chromosome are at an elevated risk for developing either a disorder on the autism spectrum or psychosis that is, any mental disorder characterised by delusions and hallucinations, including schizophrenia.
However, there has been no way to predict which child with the abnormality might be at risk for which disorder.
Researchers at University of California, Los Angeles (UCLA) and the University of Pittsburgh are the first to suggest a potential way to make that determination.
Researchers have isolated specific genetic differences in people with DiGeorge syndrome between who have autism and those who have psychosis.
DiGeorge syndrome affects roughly 1 in 2500 children born worldwide, and is the second most common genetic abnormality, after Down syndrome.
Between 30 and 40 per cent of individuals with the DiGeorge syndrome are diagnosed with a disorder on the autism spectrum, and between 25 and 30 per cent are diagnosed with a psychotic disorder. A small number are diagnosed with both autism and psychosis.
"The hope is that eventually we could identify individuals at risk for either disorder with a blood sample," said lead author Maria Jalbrzikowski, from the University of Pittsburgh.
Senior author Carrie Bearden, a professor at UCLA, and Jalbrzikowski, who was a postdoctoral fellow in Bearden's lab at the time of the study, took blood samples from 46 UCLA patients with the deletion.
They also took blood samples from 66 control subjects. They analysed the samples using a new technique developed by UCLA geneticist Steve Horvath, which allows researchers to look for patterns of genes that are connected to one another.
The analysis determined whether specific gene expression patterns were associated with psychosis or autism.
On average, people with DiGeorge syndrome and psychosis had 237 genes that showed a different pattern from the genes of people with the syndrome but without psychosis.
In a separate step, the researchers compared the genes associated with psychosis in the UCLA group of DiGeorge syndrome patients with psychosis to those of a sample of 180 Dutch patients who had been diagnosed with schizophrenia but did not have the syndrome. They found an overlap of seven genes.
The seven overlapping genes play a role in foetal brain development, suggesting that psychosis may originate during the early stages of brain development, Bearden said.
Meanwhile, the DiGeorge syndrome patients with autism differed from their counterparts without autism in the expression of 86 genes, which are likely involved in the development of the immune system.
The study was published in the journal PLOS One.