Gene that appears to be critically involved in a common birth defect has been identified by researchers from the University of Chicago and University of Alberta.
The gene causes mental retardation, motor delays, and sometimes autism.
The gene called FOXC1 is believed to contribute to Dandy-Walker malformation (DWM), a brain defect that occurs in 1 of every 5,000 births.
However, the gene is never actually expressed in the brain itself.
According to study co-author Dr Kathleen Millen, assistant professor of human genetics at the University of Chicago, FOXC1 is expressed in foetal tissue called mesenchyme.
It helps in the formation of the skull and other layers that surround and protect the brain.
"The developing skull and all the stuff around the brain actually are as important for brain development as the brain itself," Nature magazine quoted Millen as saying.
In the developing foetus, FOXC1 acts as a "master regulator" that controls the expression of other genes, which, in turn, give instructions necessary for the adjacent embryonic brain to properly form.
"It's controlling downstream genes, and some of those downstream genes we know are signalling molecules and growth factors that apparently are required for brain development," Millen said.
"When you don't have them the brain gets screwed up; not because the causative gene is expressed in the brain but because it's in the surrounding tissue," she added.
After finding the importance of the FOXC1 gene in cerebellar development in studies conducted over mice, the researchers then searched for humans lacking all or part of the gene.
Millen and colleagues, along with Ordan Lehmann, associate professor of ophthalmology and medical genetics at the University of Alberta, found 11 such patients with pediatric-onset glaucoma caused by FOXC1.
Further analysis showed that cerebellar abnormalities that proved the involvement of FOXC1 in Dandy-Walker malformation.
"These patients were essential for blaming the brain malformation on the FOXC1 gene," Millen said.
"Based on the mouse mutants we had a huge suspicion it had to be FOXC1, and the patients confirmed it," she added.
The findings have appeared in the September issue of Nature Genetics.