Researchers have discovered nine new genes linked to the most severe type of childhood speech disorder (CAS) -- apraxia, in which a child has difficulty making accurate movements when speaking.
The research, led by the Murdoch Children's Research Institute (MCRI), the University of Melbourne and the Walter and Eliza Hall Institute of Medical Research, analysed the genetic make-up of 34 affected children and young people and showed that variations in nine genes likely explained apraxia in 11 of them.
The genetic variations were caused by spontaneously and not inherited from their parents, the study, published in the journal Neurology, said.
One in every 1,000 children
According to the researchers, one in 1,000 children has apraxia, and despite intensive investigation, the genetic origins of this debilitating speech disorder have remained largely unexplained, until now.
"Apraxia is a distinctive, socially debilitating clinical disorder, and understanding its molecular basis is the first step towards identifying precision therapy approaches," said study lead researcher Angela Morgan from the University of Melbourne in Australia.
"Kids with apraxia typically have problems developing speech from infancy, with a history of poor feeding, limited babbling, delayed onset of first words, and highly unintelligible speech into the preschool years. Diagnosis is usually made when they are around age three," Professor Morgan said.
Eight of the nine genes are critical in a process which turns specific language genes "on" or "off" by binding to nearby DNA, the study said.
"We found these eight genes are activated in the developing brain. This suggests there is at least one genetic network for apraxia, all with a similar function and expression pattern in the brain," she said.
The researchers said that the new genetic findings would help neuroscientists and speech pathologists develop more targeted treatments for children.