Israeli scientists have created a new breakthrough treatment that may prevent children born with genetic mutations that cause deafness from losing their hearing.
The study from Tel Aviv University (TAU), Prof. Karen Avraham of the Department of Human Molecular Genetics and Biochemistry at TAU’s Sackler Faculty of Medicine and Sagol School of Neuroscience, found that by injecting a synthetic virus into mice that carried a normal version of the defective gene found in affected humans, the defect was fixed. One of Avraham’s students, Shahar Taiber, explained, “We injected the virus into the inner ear of the mice, so that it entered the hair cells and released its genetic payload. By so doing, we repaired the defect in the hair cells and enabled them to mature and function normally.”
The study stated, “Syne4 deficiency leads to hearing loss in humans. In this work, auditory function was rescued in Syne4 knockout mice by a synthetic AAV that enables safe and efficient transduction of hair cells in the cochlea.” It added, “There are currently over 120 genes associated with inherited deafness.” The abstract concluded, “Uncertainties remain regarding the durability of the treatment and the time window for intervention in humans, but our results suggest that gene therapy has the potential to prevent hearing loss in humans with SYNE4 mutations.”
“One in every 200 children is born with a hearing impairment, and one in every 1,000 is born deaf. In about half of these cases, deafness is caused by a genetic mutation. A hundred different genes are associated with hereditary deafness,” Israel 21C, which reported the breakthrough, noted.
Avraham explained, “In this study we focused on genetic deafness caused by a mutation in the gene SYNE4 – a rare deafness discovered by our lab several years ago in two Israeli families, and since then identified in Turkey and the UK as well. Children inheriting the defective gene from both parents are born with normal hearing, but they gradually lose their hearing during childhood. The mutation causes mislocation of cell nuclei in the hair cells inside the cochlea of the inner ear, which serve as soundwave receptors and are essential for hearing. This defect leads to the degeneration and eventual death of hair cells.”
Prof. Jeffrey Holt from Boston Children’s Hospital and Harvard Medical School, who worked on the study, asserted, “The findings are most promising. Treated mice developed normal hearing, with sensitivity almost identical to that of healthy mice who do not have the mutation.”
Dr. Wade Chien from the US National Institute on Deafness, who did not work on the study, echoed, “This is an important study that shows that inner-ear gene therapy can be effectively applied to a mouse model of SYNE4 deafness to rescue hearing. The magnitude of hearing recovery is impressive. This study is a part of a growing body of literature showing that gene therapy can be successfully applied to mouse models of hereditary hearing loss, and it illustrates the enormous potential of gene therapy as a treatment for deafness.”