Genetic screening at birth could reveal a child's risk of developing mental illness and pave the way for early therapy, Queensland neuroscientists say.

Researchers have examined the genes of patients with mental illnesses such as ADHD, autism spectrum disorder and schizophrenia.

These patients showed combinations of genes that indicate a risk of developing a particular illness, the Queensland Brain Institute team says.

By arranging the thousands of relevant genes into a complex network, Associate Professor Charles Claudianos and Dr Alex Cristino say they've developed an analytical tool to predict which disease would arise from a certain genetic combination.

"Currently, developmental brain disorders like autism and ADHD are diagnosed by observing behavioural and mental abnormalities in children, such as delayed language development and impaired memory and learning," the pair said in a statement on Wednesday.

Their five-year goal is to screen the DNA of newborns and older children to make a molecular diagnosis, determining the child's risk of developing a mental illness or improving the accuracy of an existing diagnosis based on behaviour.

"Such an early diagnosis would allow interventions such as speech therapy and intensive education to be started early in life; programs which have been shown to significantly improve learning outcomes in children," they said.

The researchers, who are sharing their work at this week's Australian Neuroscience Society annual meeting in Melbourne, hope to develop their work further as part of a proposed new co-operative research centre for autism.

If approved by the federal government, the centre would receive more than $100 million in funding from the commonwealth and in-kind donations and help grow their understanding of mental illnesses, they said.