However, the decision not to order a CT scan before or after GJB2 test results isn’t so simple. A substantial number of patients with GJB2 mutations receive cochlear implants and will need imaging prior to surgery, Dr. Buchman said. “You will know by the degree of hearing loss,” he said, adding that it may sometimes be better to order imaging and genetic tests together.
Explore This IssueJune 2013
All of the specialists interviewed for this article offer GJB2 testing to families of all pediatric patients. After explanation of the process and benefits of testing, most families are interested, they report. Those benefits, Dr. Buchman said, include the peace of mind that comes from knowing the cause is genetic rather than the result of something the mother did during pregnancy. Genetic testing for both GJB2 and syndromic hearing loss has identified other serious problems, can say how serious the hearing loss may ultimately be and identifies risk of recurrence. “These are all positive pieces of information,” said Dr. Buchman.
Proper counseling by otolaryngologists is a key part of the genetic testing process. Rick Friedman, MD, PhD, an otologist/
neurotologist at the House Clinic and principal investigator for Genetics of Hereditary Ear Disorders research at the House Research Institute in Los Angeles, emphasized the need to discuss the GJB2 test thoroughly when it is offered, adding that it often yields negative results. “It’s important to discuss the test and counsel parents about what a positive or negative result implies for family,” he said. For example, a positive result can give information about recurrence risk. Genetic testing usually does not change hearing loss treatment, which generally involves hearing aids or cochlear implants regardless of the cause, he added.
Families don’t always choose genetic testing, said Dr. Lalwani. Such decisions often result from lack of insurance coverage but are sometimes based on ethnic customs and religious beliefs.
Looking to More Genes and the Future
Genetic testing offers a valuable opportunity to better tailor care to individual children’s needs and will enable families to take advantage of future interventions to restore hearing, said Richard Smith, MD, director of the Iowa Institute of Human Genetics and professor and vice chair of the department of otolaryngology–head and neck surgery at the University of Iowa Carver College of Medicine in Iowa City. Researchers are now developing therapies that “will be predicated on knowing the exact genetic cause of hearing loss,” some of which have already reversed hearing loss in mice, he said.