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Christine Petit, First Scientist to Identify Hearing Loss Genes

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Christine Petit, First Scientist to Identify Hearing Loss Genes

Christine Petit was the winner of the 2007 INSERM award for medical research, the Grand Prix de la recherche médicale, for identifying the hereditary causes of hearing loss and deciphering the molecular physiology of the cochlea, the sensory organ of hearing.  Director of the INSERM joint research unit UMRS 587 Genetics and Physiology of Hearing at the Institut Pasteur, professor at the Collège de France where she holds the chair of cell genetics and physiology, director of the Institut Pasteur department of neuroscience and a member of the Académie des Sciences since 2002.

Christine Petit talks about her research and findings on hearing loss and the functioning of the cochlea at molecular level.

Gambling on genetics was a bold move in the field of hearing loss.  Can you describe the major phases in this development?
In 1991, after identifying a gene responsible for a syndrome that leads to an olfactory deficit, we examined the relevance of the genetic approach to deciphering the molecular physiology of other sensory systems.  We found that the molecular mechanisms that control the functioning of the cochlea were totally unknown owing to the very small number of cells of each of the organ's cell types.  Also, although some hearing impaired families had been studied, no gene responsible had been identified.  Consequently, it appeared that if we found the means to access these genes, we could anticipate understanding the pathogenesis in these patients, which most often concerns the cochlea and its molecular physiology. 

In 1994, we opened up the field of hereditary hearing loss to genetic analysis by studying geographically isolated hearing impaired families.  Nearly forty-five genes have now been discovered, some twenty of which in our laboratory.  All (except one), when defective, cause a lesion of the cochlea.  Then, using a multidisciplinary approach, we deciphered the molecular mechanisms involving proteins coded by the various hearing loss genes.  We were also able to reveal the predominantly hereditary cause of severe hearing loss in children.  With regard to age-related hearing loss, we now know that there are predisposing genetic factors that we are striving to research.  Such factors also exist for hearing loss resulting from noise exposure.  It must be noted that, while noise pollution in exposed workplaces is, as a general rule, fairly well controlled, this is not the case in public spaces and schools, such as school canteens.

From genes to treatments: how do you see the future?The prime objective is to identify the severest forms of hereditary hearing loss for which the cochlear implant should be effective taking into account their pathogenesis.  Now, with the identification of predisposing genetic factors to delayed hearing loss, the objective is also to research preventive and curative treatments, existing drugs included.  Gene and cell therapy approaches are conceivable in the longer term.

Such results should draw students to laboratories.  How can they be completely convinced?

We need to tell students with double degrees in physics/biology or medicine/biology that they have the appropriate training to take up today's challenges in this scientific and medical field: understanding the processing of sound information in the entire auditory system at molecular and cellular level, understanding and treating the hearing impaired.  Excellent specialists in one of these fields, with a taste for scientific interdisciplinarity, will find a wealth of issues that can be approached at different levels and in close collaboration with specialists in other fields. 

This prize recognises the work of a multidisciplinary team of some twenty people: geneticists, molecular biologists, cellular biologists, electrophysiologists, physicists, biochemists, crystallographers: imagine the wealth of exchanges!  The combination of high-level fundamental research and medical-orientated research is now not just perfectly possible, but particularly profitable.  The team is very important: the INSERM research laboratory at the Institut Pasteur department of neuroscience, is associated with the paediatric ORL department of the Armand-Trousseau children's hospital and, more recently, with a team from Université Bordeaux-2.  This organisation promotes the transfer of research results to patients.  Preventing and treating hearing loss is no longer fiction.