An international team of researchers has identified a new genetic cause for Joubert syndrome (JS), an inherited condition that affects development of the cerebellum and brainstem-the structures in the brain that coordinate movements and regulate basic functions such as breathing, swallowing, heart rate and consciousness.
This is the fifth gene that has been found to have association with Joubert syndrome. Researchers at Seattle Children's Hospital Research Institute, the University of Washington School of Medicine, and Radboud University in Nijmegen, say that their study confirms key information about the genetic changes that cause JS and cellular structures called cilia, conclusively placing JS in a class of recently identified ciliopathic conditions.
Although the disease is statistically rare, the researchers believe that their findings are important. They say that the discovery of mutation in the gene (RPGRIP1L) now paves the way for definitive DNA testing that can more conclusively diagnose JS in some patients, and also identify asymptomatic carriers who might unknowingly pass the condition to their future children.
Apart from identifying a fifth gene for JS, the study also sheds light on the role of cilia in this disease and possibly others.
It found that defects in the functions of cilia, tiny projections on cell surfaces that allow the inside of cells to communicate with their outside environment, lead to various newly identified syndromes called ciliopathies.
Published in the journal Nature Genetics, the study describes a genetic change that prevents interaction between two particular cilia proteins, presumably disrupting cilia function and causing JS.
It links JS to other diseases like Leber congenital amaurosis, Senior-Loken syndrome, and nephronophthisis, the most common genetic cause of kidney failure in children. All these conditions share disruptions in the protein networks of cilia.
The study also exemplifies the power of international collaborative research, an increasingly important trend in biomedical discoveries.