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Ebermann, I., Scholl, H. P., Charbel Issa, P., Becirovic, E., Lamprecht, J., Jurklies, B. et al. A novel gene for Usher syndrome type 2: mutations in the long isoform of whirlin are associated with retinitis pigmentosa and sensorineural hearing loss. Hum. Genet. 121, 203-211

Institute of Human Genetics, University Hospital of Cologne, Kerpener Str. 34, 50931 Cologne, Germany.
Human Genetics (Impact Factor: 4.52). 05/2007; 121(2):203-11. DOI: 10.1007/s00439-006-0304-0
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ABSTRACT Usher syndrome is an autosomal recessive condition characterized by sensorineural hearing loss, variable vestibular dysfunction, and visual impairment due to retinitis pigmentosa (RP). The seven proteins that have been identified for Usher syndrome type 1 (USH1) and type 2 (USH2) may interact in a large protein complex. In order to identify novel USH genes, we followed a candidate strategy, assuming that mutations in proteins interacting with this "USH network" may cause Usher syndrome as well. The DFNB31 gene encodes whirlin, a PDZ scaffold protein with expression in both hair cell stereocilia and retinal photoreceptor cells. Whirlin represents an excellent candidate for USH2 because it binds to Usherin (USH2A) and VLGR1b (USH2C). Genotyping of microsatellite markers specific for the DFNB31 gene locus on chromosome 9q32 was performed in a German USH2 family that had been excluded for all known USH loci. Patients showed common haplotypes. Sequence analysis of DFNB31 revealed compound heterozygosity for a nonsense mutation, p.Q103X, in exon 1, and a mutation in the splice donor site of exon 2, c.837+1G>A. DFNB31 mutations appear to be a rare cause of Usher syndrome, since no mutations were identified in an additional 96 USH2 patients. While mutations in the C-terminal half of whirlin have previously been reported in non-syndromic deafness (DFNB31), both alterations identified in our USH2 family affect the long protein isoform. We propose that mutations causing Usher syndrome are probably restricted to exons 1-6 that are specific for the long isoform and probably crucial for retinal function. We describe a novel genetic subtype for Usher syndrome, which we named USH2D and which is caused by mutations in whirlin. Moreover, this is the first case of USH2 that is allelic to non-syndromic deafness.

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    • "To date, about 14 different USH loci have been mapped on different chromosomes (see http://hereditaryhearingloss.org/), and 10 of the corresponding genes have been identified (Fig. 1). These genes encode six USH1 proteins – myosin VIIa (USH1B) [22], harmonin (USH1C) [23] [24], cadherin-23 (USH1D) [25] [26], protocadherin-15 (USH1F) [27] [28], SANS (USH1G) [29], and CIB2 (USH1J) [30], three USH2 proteins – usherin (USH2A) [31], VLGR1 (USH2C) [32], and whirlin (USH2D) [33], and one USH3 protein, clarin-1 (USH3A) [34] (see Fig. 1). In addition, PDZD7 has been shown to act as a modifier of USH2 gene function [35]. "
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    ABSTRACT: The Usher syndrome (USH) is the most prevalent cause of inherited deaf-blindness. Three clinical subtypes, USH1-3, have been defined, and ten USH genes identified. The hearing impairment due to USH gene defects has been shown to result from improper organisation of the hair bundle, the sound receptive structure of sensory hair cells. In contrast, the cellular basis of the visual defect is less well understood as this phenotype is absent in almost all the USH mouse models that faithfully mimic the human hearing impairment. Structural and molecular interspecies discrepancies regarding photoreceptor calyceal processes and the association with the distribution of USH1 proteins have recently been unravelled, and have led to the conclusion that a defect in the USH1 protein complex-mediated connection between the photoreceptor outer segment and the surrounding calyceal processes (in both rods and cones), and the inner segment (in rods only), probably causes the USH1 retinal dystrophy in humans.
    Comptes rendus biologies 03/2014; 337(3):167-77. DOI:10.1016/j.crvi.2013.12.004 · 1.68 Impact Factor
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    • "USH2, which has the moderate clinical symptoms, accounts for about 70 % of all Usher syndrome cases (Hartong et al. 2006). Three genes have been identified that associate with USH2, which are Usherin (USH2A), Vlgr1 (USH2C), and Whirlin (USH2D; Ebermann et al. 2007; Eudy et al. 1998; Weston et al. 2004). Recently, PDZD7, which encodes a PDZ-domain containing protein, was identified as a modifier gene for USH2A and might contribute to a digenic form of USH2C (Ebermann et al. 2010). "
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    ABSTRACT: The very large G protein coupled receptor (Vlgr1) is a member of adhesion receptors or large N-terminal family B-7 transmembrane helixes (LNB7TM) receptors within the seven trans-membrane receptor superfamily. Vlgr1 is the largest GPCR identified to date; its mRNA spans 19 kb and encodes 6,300 amino acids. Vlgr1 is a core component of ankle-link complex in inner ear hair cells. Knock-out and mutation mouse models show that loss of Vlgr1 function leads to abnormal stereociliary development and hearing loss, indicating crucial roles of Vlgr1 in hearing transduction or auditory system development. Over the past 10 or so years, human genetics data suggested that Vlgr1 mutations cause Usher syndromes and seizures. Although significant progresses have been made, the details of Vlgr1's function in hair cells, its signaling cascade, and the mechanisms underlying causative effects of Vlgr1 mutations in human diseases remain elusive and ask for further investigation.
    Journal of Molecular Neuroscience 11/2012; 50(1). DOI:10.1007/s12031-012-9911-5 · 2.76 Impact Factor
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    • "The patients in the German family had mild to moderate hearing loss (Ebermann et al., 2007a) while the Portuguese family had variable degree of hearing loss with post lingual onset which was progressive in nature (Audo et al., 2011). In the German family two mutations in WHRN were detected in compound heterozygosity, involving a nonsense mutation in exon 1 and a splice site mutation in intron 2. The splice site mutation causes an in-frame skipping of the second exon and is predicted to result in production of an aberrant protein (Ebermann et al., 2007a). "
    Hearing Loss, 03/2012; , ISBN: 978-953-51-0366-0
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