Animal study: gene therapy to treat hereditary hearing loss

Usher syndrome

Research with mice

Researchers in the United States have been able to restore hearing in genetically modified mice mimicking Usher Syndrome, a genetic condition that causes deafness, dizziness, and blindness.

The team, from the National Institute on Deafness and Other Communication Disorders (NIDCD) and Johns Hopkins School of Medicine, Baltimore, Maryland, used deaf whirler mice in their study, a model of human Usher syndrome, which is characterized by hearing loss, dizziness, and progressive vision loss.

The mice have a recessive mutation in the whirlin gene (WHRN homolog), which renders hair cell stereocilia short and dysfunctional. In their study, wild-type whirlin complementary DNA (cDNA) was transferred to the inner ears of neonatal test mice using an adeno-associated virus (AAV) by injection into the posterior semicircular canal. AAVs are currently being used in many genetic transfer studies.

Behavioral measures were used to assess balance function, specifically circling behavior and swim testing. Hearing tests were performed using auditory brainstem response measurements. Unilateral whirlin gene therapy injection made it possible to restore balance function and to improve hearing in whirler mice for at least 4 months.

In a press release, Dr. Wade Chien, senior research involved in the study, commented: “Inner ear gene therapy offers tremendous potential as a new way to help patients with hearing loss and dizziness.”

Source: UPI; K. Isgrig, et al. Gene Therapy Restores Balance and Auditory Functions in a Mouse Model of Usher Syndrome. Molecular Therapy 2017 Mar 1;25(3):780-791.