Over half of all deafness cases that develop from birth through infancy in industrial nations have a genetic bases. A significant number of people who develop deafness later in life also have a genetic propensity, researchers from Miami University and the University of Miami School of Medicine reported in the journal Genetic Testing and Molecular Biomarkers.

According to WHO (World Health Organization), more than 360 million people worldwide live with disabling hearing loss.

So far, geneticists have identified 1,000 mutations in 64 genes in the human genome that have been associated with deafness.

The authors explained that next-generation DNA sequencing technologies are accelerating the identification of genetic variants that cause deafness.

In this latest report – “Next Generation Sequencing in Genetic Hearing Loss” – Susan Blanton, Mustafa Tekin, Xue Zhong Liu and Denise Yan gathered and examined data on the advances in high-throughput, massively parallel DNA sequencing that amplify and repeatedly sequence only certain regions of the human genome where genes associated with hearing loss are probably located.

This strategy is called “targeted resequencing”. Scientists are able to locate disease-related gene mutations much faster than searching through the whole genome.

So far, over 1,000 DNA variants at over 130 sites in the human genome that have been identified to cause hearing loss and are not linked to any other symptoms or syndromes have been located.

The authors wrote:

“Over the next decade, most of the variant genes responsible for deafness will be identified and such knowledge will lead to the development of practical treatments.”

Kenneth I. Berns, MD, PhD, Editor-in-Chief of Genetic Testing and Molecular Biomarkers said “Knowledge of the genetic lesions underlying deafness will greatly assist development of targeted therapy.”

Genetic patch partially restored hearing – scientists at Rosalind Franklin University of Medicine and Science in Chicago used a tiny genetic patch to partially restore hearing and balance in deaf mice with Usher syndrome. Their study was reported in Nature Medicine (February 2013 issue).

The scientists emphasized that their study is still in its early stages, but could eventually develop into new therapies for Usher syndrome, a congenital hearing disorder – most patients with Usher syndrome also become blind.

Genetic marker for age-related hearing loss – scientists at the University of South Florida identified a genetic biomarker for age-related deafness (presbycusis). They claim their discovery is a major breakthrough in understanding and preventing a condition of aging that affects approximately 30 million people in the United States. They added that the genetic mutation carried by those who eventually develop presbycusis is linked to speech processing abilities in seniors. Their findings were published in the Hearing Research (October 2012 issue).

Written by Christian Nordqvist