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J. Kaplan, S. Gerber, D. Bonneau, A. Munnich, J.–L. Dufier, J.–M. Rozet; Usher Syndrome Type 1a: From Myth to Reality . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4605.
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© ARVO (1962-2015); The Authors (2016-present)
To check the reality of the "French variety" of Usher Type 1A, thirteen years after its report, in light of unexpected data that occured since then.
The USH1A locus was described in 1992 in eight families originating from the small area of the Poitou–Charentes region around the town of Bressuire in France. Subsequently, an enlarged panel USH1 families was considered including the eight original USH1A families and two additonnal ones hailing from Bressuire. Surprisingly, one of these two additional families appeared unlinked to the USH1A locus on 14q32.1. Besides, an additional affected individual in one of the original USH1A families turned to be haplodifferent to his affected sibs at this locus. Therefore we decided to screen for mutations the major USH1 gene, the myosin VIIA in one affected individual of each family using direct sequencing.
Among the 10 families originating from Bressuire, 7/10 harboured mutations in the myosin VIIA gene, 1/10 was compatible with the USH1D and USH1E loci, 1/10 excluded all seven hitherto identified USH1 loci. No DNA was available for further linkage studies in the last family.
The recent study of additonal families affected with Usher syndrome type 1 originating from Poitou–charentes clearly showed that i)the USH1A locus does not exist; ii) the myosin VIIA gene is the major USH1 gene and finally iii) that, in our series, one family excluded all USH1 loci suggesting that at least one additional gene should be identified.
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