A Genetic Basis for Mechanosensory Traits in Humans

Henning Frenzel,Kathrin Saar,José M Millán,Franz Rüschendorf,Jörg Bohlender,Teresa Jaijo,Jens Tank,Gary R Lewin,Daniela Schiska,Jens Jordan,Bärbel Wohlleben,Katrin Pinsker,Stefan G Lechner,Manfred Gross

doi:10.1371/journal.pbio.1001318

Abstract

Author SummaryIn humans many genes have been identified that cause deafness when mutated, but no equivalent genes have been identified that are required for touch. Here, we asked whether genes that influence hearing can also influence touch. Using identical and non-identical human twins it was possible to show that touch performance is substantially influenced by genes. Furthermore, people who have excellent hearing are more likely to have a fine sense of touch and vice versa. Interestingly, people who suffer from congenital deafness have a higher chance of having poor touch performance. In a genetically defined form of human deafness, Usher syndrome type II, a single mutated gene was identified that also impairs touch. Touch and hearing are thus intricately intertwined and there may be other touch/hearing genes waiting to be discovered.

Highlights

All animals are equipped with a range of specialized sensory cells whose prime function is to detect mechanical force
We found touch sensitivity to be impaired in a cohort of individuals carrying pathogenic mutations in the USH2A gene (MIM:608400), but not in other cases of Usher syndrome
Our main aim was to assess mechanosensory-related phenotypic traits, which included two measures of touch sensitivity: a grating orientation task, which assesses the participants’ finger tip touch acuity in millimeters, and a vibration detection test, which measures the vibration detection threshold (VDT) for a sinusoidal vibratory stimulus delivered to the finger at 125 Hz

Summary

Introduction

All animals are equipped with a range of specialized sensory cells whose prime function is to detect mechanical force. The most familiar of these sensory systems are hearing and touch, but mechanosensory cells detect important stimuli that are not consciously perceived, for example, changes in blood pressure. We reasoned that since the prime function of different sensory cells is to detect mechanical force they may utilize a common set of mechanosensory proteins for this function. According to this hypothesis genetic variation affecting the function of mechanosensory proteins would be predicted to quantitatively change more than one mechanosensory trait. Non-syndromic sensorineural hearing loss is commonly caused by single gene mutations, which primarily affect the function of the sensory hair cells that detect movement of the basilar membrane induced by sound. Sensorineural deafness often manifests from birth and some of the responsible genes encode components of the mechanotransduction apparatus of the hair cell that transforms mechanical force into electrical signals [2,3,4]

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