Deafness linked to heightened sense of touch

A genetic mutation that causes deafness in humans and mice also causes heightened touch sensitivity, reports a study published online this week in Nature Neuroscience. Humans with a mutation in a gene called KCNQ4, which codes for a particular type of neuronal ion channel in the ear, have a form of heritable and slowly progressing hearing loss. Mice lacking this gene or genetically-engineered mice that expressed the same human mutation also are deaf, and their sensory cells in their ears show no response to sounds and slowly die. Gary Lewin and colleagues now show that this gene, KCNQ4, is also expressed in a subset of neurons responsible for sensing touch. They found that mice genetically engineered to express a non-functional protein from the KCNQ4 gene displayed greater sensitivity to certain types of touch, particularly those with low frequency vibrations. Human deaf subjects with the same mutation in the KCNQ4 gene also performed better in touch acuity tests.