New Usher Syndrome Type 1 Gene Identified

October 09, 2012
In a research paper recently published in the journal Nature Genetics, an international team of scientists reported the identification of a new gene linked to Usher syndrome, the world’s leading cause of combined deafness and blindness. Usher-causing mutations in the gene, called CIB2, were found in a Pakistani family.

Subsequent experiments by the team revealed that, when it’s not mutated, CIB2 leads to the production of a protein critical to the development and function of hair-like cells responsible for hearing and vision in zebrafish and flies. The scientists also found the CIB2 protein in the photoreceptors of mice.

“The discovery of the CIB2 gene and its role in the retina and inner ear provide critical information for why vision and hearing are lost and targets for potential for treatments,” says Dr. Stephen Rose, chief research officer, Foundation Fighting Blindness. “This advancement underscores why genetic research is critical to tackling Usher syndrome and virtually all other inherited retinal degenerations. Several other global research efforts like this one are also trying to uncover new genes linked to retinal disease and deafness.”

The study’s lead investigator, Dr. Zubair Ahmed, of the Cincinnati Children’s Hospital Medical Center, says that the research team is now screening people in the United States, Korea and India to determine the frequency of Usher-related CIB2 mutations in various groups. The scientists have also developed a mouse model of the disease to better understand how vision and hearing are affected. The model will be used to test potential therapeutic agents.

The disease caused by certain mutations in CIB2 has been labeled as Usher syndrome type 1J. CIB2 is the 14th genetic region to be linked to Usher syndrome. (In some cases, researchers haven’t found the actual gene, but have narrowed their search to a specific location.) People with Usher syndrome categorized as type 1 generally have profound hearing loss and balance problems at birth with progressive vision loss from retinitis pigmentosa diagnosed in childhood.

Other scientists contributing to this effort were from: the Cincinnati Children’s Hospital Medical Center; the University of Cincinnati; the National Institute on Deafness and Other Communication Disorders (National Institutes of Health); Baylor College of Medicine; the University of Kentucky; the University of the Punjab (Pakistan); the University of Miami (Florida); the University of North Carolina; Quaid-A-Azam University (Pakistan); Balochistan University of Information Technology (Pakistan); Allama Iqbal Medical College (Pakistan); the University of Lahore (Pakistan); and Bahauddin Zakariya University (Pakistan).