Genetic Hearing Test Moves Ahead Goal Is to Identify Sensorineural Loss Earlier Features
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Features  |   July 01, 2005
Genetic Hearing Test Moves Ahead
Author Notes
  • Dee Naquin Shafer, an assistant managing editor of The ASHA Leader, can be reached at dshafer@asha.org.
    Dee Naquin Shafer, an assistant managing editor of The ASHA Leader, can be reached at dshafer@asha.org.×
Article Information
Hearing Disorders / Special Populations / Genetic & Congenital Disorders / Features
Features   |   July 01, 2005
Genetic Hearing Test Moves Ahead
The ASHA Leader, July 2005, Vol. 10, 5-27. doi:10.1044/leader.FTR3.10092005.5
The ASHA Leader, July 2005, Vol. 10, 5-27. doi:10.1044/leader.FTR3.10092005.5
A new genetic test under development at Cincinnati Children’s Hospital Medical Center (CCHMC) could be used to identify the genetic cause of inner ear hearing loss in infants as young as one day old. The test would be both faster and less expensive than current functional methods, provided the cause of hearing loss is genetic in nature.
CCHMC researchers are collaborating with scientists at Harvard Partners Group in Boston and Affymetrix Corp. in California. The scientists are using gene chips capable of holding about 28,000 base pairs of DNA information to look at a small segment of genes specifically associated with sensorineural hearing loss in the early years of life.
The technique allows researchers to rapidly screen nine genes, with results returned in a few weeks. It would replace the standard sequencing currently used, which can take months. Current sequencing techniques are limiting in their ability to analyze massive amounts of genetic material. John H. Greinwald, Jr., a pediatric otolaryngologist, is taking the lead at CCHMC. Greinwald said the chip, made by Affymetrix Corp. is in its first version. More genes will be added to a second version after the initial study helps determine other pertinent genes.
The GJB2 gene has been identified as a cause for many cases of inner ear hearing loss, Greinwald said. “We want to find out the second, third, and fourth genes that are the most common [causes]. What genes should we screen for in particular population bases?”
Scientists at the hospital have completed a technical proof of principal study. They are now performing a validation trial to analyze if the gene chip can perform as expected from a clinical standpoint.
Greinwald said the group is planning to enroll approximately 190 people for the validation trial. It will not be limited to infants, but will include children who have been followed since their hearing loss was documented before age 1. The study group will include “singletons,” or children who are the only one in the family with hearing loss. The other part of the study will be made up of “sib-pairs” (more than two children per family with inner ear hearing loss), which would definitively indicate the possibility of a genetic cause of hearing loss.
“We’re going to look at the participants and compare the two technologies: the gene chip to standard sequencing,” Greinwald said. “We hope that the genes we have selected to screen will be the key genes involved in early onset hearing loss in children.”
The test could be available in the first quarter of 2006. After the validation trial is completed, it must be certified with the College of American Pathologists and with the CMS (Centers for Medicare and Medicaid Services) and CLIA Program (Clinical Laboratory Improvement Amendments).
“We will probably do a clinical test with a larger sample of patients for a newer version chip,” he said. The scientists hope to work with the National Institutes of Health on that phase.
In its pilot phase, the gene chip was supported by the CCHMC Translational Research Initiative. It is currently supported by the state of Ohio through a Biomedical Research and Technology Transfer (BRTT) trust fund grant.
CCHMC is still seeking “sib-pairs” for the study. For more information contact the Center for Hearing and Deafness Research at 513-636-4870, or chdr@chdr.org. The study was published in the December 2004 issue of Otolaryngology-Head and Neck Surgery.
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July 2005
Volume 10, Issue 9