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The origin of blindness identified for some types of hearing loss and visual impairment

Researchers from the Institut Pasteur, the Institut de la Vision, Inserm and the Université Pierre et Marie Curie have shed light on the origin of blindness that occurs in Usher I (the most common cause of deafness-blindness in humans). The scientists also demonstrated why the rat, the only animal model available today for this illness, does not suffer from the same blindness observed in humans. This work involves directing future research towards producing a primate animal model. The latter will then make it possible to progress towards a therapy-based approach for blindness in patients suffering from Usher I. This research was published on 8 October in the Journal of Cell Biology.

Usher syndrome is a genetic illness that causes congenital deafness and progressive visual impairment caused by retinitis pigmentosa. The prevalence rate of Usher syndrome is estimated at 1/30,000. Currently, a good level of care is provided for patients with hearing disorders. However, today, there is no treatment able to stop the end result of retinitis pigmentosa.

Research conducted by Professor Christine Petit, head of the “Genetics and physiology of hearing” research unit at the Institut Pasteur, in collaboration with Dr Aziz El-Amraoui (Institut Pasteur) and Professor José-Alain Sahel (Institut de la Vision), has provided fresh grounds for hope: researchers have just discovered the origin of retinitis pigmentosa in patients suffering from Ushers  I. It stems from a fault in the organization of cell structures essential to maintain vision, calyceal processes.  This failure is caused by the malfunction of one or several proteins; in this case, five were identified by the researchers that ensured cohesion in the calyceal processes. It was possible to observe the structure of the calyceal processes in high definition using electronic microscopic techniques (see photos).

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©Copyright Institut Pasteur / Cataldo Schietroma et Vincent Michel

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Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice, Journal of Cell Biology, october, 15, 2012.

Iman Sahly1,3,4, Eric Dufour1,3,4, Cataldo Schietroma1,3,4, Vincent Michel2,3,4, Amel Bahloul2,3,4, Isabelle Perfettini2,3,4, Elise Pepermans2,3,4, Amrit Estivalet1,3,4, Diane Carette2,3,4, Asadollah Aghaie1,3,4, Inga Ebermann2,3,4, Andrea Lelli2,3,4, Maria Iribarne2,3,4, Jean-Pierre Hardelin2,3,4, Dominique Weil2,3,4, José-Alain Sahel1,5, Aziz El-Amraoui2,3,4 , and Christine Petit1,2,3,4,6

1 Institut de la Vision, Syndrome de Usher et autres Atteintes Rétino-Cochléaires, Paris, France
Institut Pasteur, Unité de Génétique et Physiologie de l’Audition, Paris, France
Inserm UMRS587, Paris, France
Inserm UPMC, Paris 6, France
Inserm UMRS968, Institut de la Vision, Département de Génétique, Paris, France
Collège de France, Paris, France