High tech genetic sequencing enables screening for hereditary hearing loss

January 2011

Using a combination of special techniques to capture specific DNA sequences and high-throughput technology to sequence them, scientists from the Baylor College of Medicine Human Genome Sequencing Center and the University of Iowadeveloped a test to simultaneously screen more than 50 genes known to cause hearing loss and deafness - a time- and cost-saving analysis that will provide important answers to parents and deaf children in the future.

"This use of massively parallel sequencing demonstrates the value of this kind of technology in identifying and diagnosing the source of disease," said Dr. Richard Gibbs, director of the Human Genome Sequencing Center, where the sequencing took place.

Technology directly benefits patients

"The really exciting aspect of this news is the fact that we're now bringing the technology that the genome center has worked so hard to develop directly to the clinic and to the direct benefit of patients," said Dr. Steve Scherer, associate professor in the BCM Human Genome Sequencing Center and an author of the report that appears online today in the Proceedings of the National Academy of Sciences.

The technology, which Iowa researchers dubbed OtoSCOPE (otologic sequence capture of pathogenic exons), may soon become a test offered through the Molecular Otolaryngology and Renal Research Laboratory at the University of Iowa.

In the past, researchers looked for the genetic causes of hearing loss one gene at a time. It was a slow and expensive process, said Eliot Shearer, a University of Iowa M.D./Ph.D. student and another co-author. Knowing which gene mutation causes the hearing loss can give families information on how severe the deafness will be and the chance of having another child with the disorder. It can also help doctors find the best treatment - such as hearing aids or cochlear implants.

Early intervention important

In some cases, deafness is part of a syndrome that can include other problems. Usher Syndrome, for example, is the most common cause of deaf-blindness in the United States. While children lose hearing early, blindness develops at around age 10.

Early intervention can help slow vision loss, said Dr. Michael Hildebrand, a postdoctoral fellow at the University of Iowa and a co-author of the report.

In the study, researchers tested 10 patients. In three, the gene mutation was already known. One sample was known to have no deafness mutations. The remaining six had unknown gene mutations. The genetic screen was able to identify the gene mutation in five of the six unknowns.

Others who took part in this work include Donna Muzny, Dr. Yi Han, Dr. Min Wang and Fiona Ongeri of the BCM Human Genome Sequencing Center as well as Adam P. DeLuca Kyle R. Taylor, Jose Gurrola II, Todd Scheetz and Richard J.H. Smith, at the University of Iowa.

Funding for the study came from the National Institutes of Health, the National Institute on Deafness and other Communication Disorders, National Health and Medical Research Council in Australia, and the Doris Duke Charitable Foundation.