Genetic Pathway of Rare Facial Malformation in Children Pinpointed

Researchers at Seattle Children's Research Institute and their collaborators have discovered a pair of defective genes that cause a rare congenital malformation syndrome that can make it impossible for the child to breathe or eat properly without reparative surgery. They found two genes known as PLCB4 and GNAI3 in a genetic pathway that affects children with auriculocondylar syndrome (ACS). ACS is a rare disorder in which a child's bottom jaw develops as an upper jaw and, in some cases, incorrectly fuses to the base of the skull.

3D CT scan of child with ACS. Lower jaw is small and malformed (left); same aged child with normal jaw (middle); lower jaw of child with ACS inverted over upper jaw of normal skull (right). (Credit: Image courtesy of Seattle Children's)

"Although ACS is rare, our findings suggest that these genes may also play a role in more common disorders of the jaw and ears," said Dr. Cunningham, who is also chief of the division of craniofacial medicine and professor of pediatrics in the Department of Pediatrics at the University of Washington School of Medicine. "It's possible that more common jaw problems, like the lower jaw abnormality known as Robin sequence and other skull and facial abnormalities such as craniofacial microsomia, are also caused by genes in this pathway."  Of the five cases studied, two of the parents did not have this condition but were carriers for the mutation. "Now that we know the genetic pathway for ACS, we will be able to better identify and counsel people who have normal facial appearances but carry these genes, about the likelihood of passing on this mutation to their children,'' Dr. Cunningham said.