An international study by researchers at Seattle Childrens Hospital Research Institute, the University of Washington School of Medicine, and Radboud University in Nijmegen, Netherlands has identified a new genetic cause for Joubert syndrome (JS). Joubert syndrome is 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. The study, published in the June 10, 2007 issue of Nature Genetics, 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. Though the disease is statistically rare and four other genetic markers have been previously identified, researchers believe these findings are important.

Joubert syndrome can result in developmental delay, poor physical coordination, irregular breathing, visual impairment, kidney failure and extra digits. Diverse symptoms may occur making diagnosis difficult, though patients typically feature a characteristic configuration of the brainstem and cerebellum on magnetic resonance imaging (MRI), where the abnormally developed brain stem resembles the shape of a molar tooth. The researchers 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.

In addition to identifying a fifth gene for JS, the study also sheds light on the role of cilia in this disease and possibly others. Primary cilia are tiny projections on cell surfaces that allow the inside of cells to communicate with their outside environment. Recent research has found that defects in cilia function lead to various newly identified syndromes called ciliopathies. T
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Contact: Teri Thomas
teri.thomas@seattlechildrens.org
206-987-5213
Children's Hospital and Regional Medical Center of Seattle
11-Jun-2007