Background: Usher syndrome (USH) combines sensorineural deafness with blindness. It is inherited in an autosomal recessive mode. Early diagnosis is critical for adapted educational and patient management choices, and for genetic counseling. To date, nine causative genes have been identified for the three clinical subtypes (USH1, USH2 and USH3). Current diagnostic strategies make use of a genotyping microarray that is based on the previously reported mutations. The purpose of this study was to design a more accurate molecular diagnosis tool. Methods: We sequenced the 366 coding exons and flanking regions of the nine known USH genes, in 54 USH patients (27 USH1, 21 USH2 and 6 USH3). Results: Biallelic mutations were detected in 39 patients (72%) and monoallelic mutations in an additional 10 patients (18.5%). In addition to biallelic mutations in one of the USH genes, presumably pathogenic mutations in another USH gene were detected in seven patients (13%), and another patient carried monoallelic mutations in three different USH genes. Notably, none of the USH3 patients carried detectable mutations in the only known USH3 gene, whereas they all carried mutations in USH2 genes. Most importantly, the currently used microarray would have detected only 30 of the 81 different mutations that we found, of which 39 (48%) were novel. Conclusions: Based on these results, complete exon sequencing of the currently known USH genes stands as a definite improvement for molecular diagnosis of this disease, which is of utmost importance in the perspective of gene therapy.

Mitochondrial DNA (mtDNA) mutations have been implicated in non-syndromic hearing loss either as primary or as predisposing factors. As only a part of the mitochondrial genome is usually explored in deafness, its prevalence is probably under-estimated. Among 1350 families with non-syndromic sensorineural hearing loss collected through a French collaborative network, we selected 29 large families with a clear maternal lineage and screened them for known mtDNA mutations in 12S rRNA, tRNASer(UCN) and tRNALeu(UUR) genes. When no mutation could be identified, a whole mitochondrial genome screening was performed, using a microarray resequencing chip: the MitoChip version 2.0 developed by Affymetrix Inc. Known mtDNA mutations was found in nine of the 29 families, which are described in the article: five with A1555G, two with the T7511C, one with 7472insC and one with A3243G mutation. In the remaining 20 families, the resequencing Mitochip detected 258 mitochondrial homoplasmic variants and 107 potentially heteroplasmic variants. Controls were made by direct sequencing on selected fragments and showed a high sensibility of the MitoChip but a low specificity, especially for heteroplasmic variations. An original analysis on the basis of species conservation, frequency and phylogenetic investigation was performed to select the more probably pathogenic variants. The entire genome analysis allowed us to identify five additional families with a putatively pathogenic mitochondrial variant: T669C, C1537T, G8078A, G12236A and G15077A. These results indicate that the new MitoChip platform is a rapid and valuable tool for identification of new mtDNA mutations in deafness.

First, to assess for the performance of the Carina placed on the round window at various European centers; second, to study the follow-up after 2 years and discuss limitations and technical issues; and finally, to further develop our understanding of the principles of acoustic transfer through the round window. Eleven patients were included in this retrospective study (7 women and 4 men) from 7 European tertiary referral hospitals (4 centers in France, 2 in Belgium, 1 in Spain). The mean age was 50.8 years (35-71 yr). All patients have multiple previous surgeries (>3 surgical procedures) for otosclerosis (3 patients) or chronic otitis media (8 patients), and in all cases, the stapes was not accessible due to obliteration by sclerotic tissue. Preoperative and postoperative air conduction, bone conduction, as well as aided and unaided thresholds and speech scores were measured. No significant differences were observed between preoperative and postoperative air-conduction and bone-conduction pure-tone averages. The average free field functional gain obtained with the implant ranged from 22 to 42 dB at each individual frequency, with a mean of 29 ± 5 dB across all audiometric frequencies. Word recognition scores demonstrated significant differences between unaided and implant-aided conditions. Complications included 2 cases of postoperative infection (including 1 anacusis) that required explantation, and 1 case reduced initial benefit, followed by a nonfunctioning device. In 10 patients, postoperative hearing was unchanged. The 8 other patients are using their implant daily. These results show that this option is valid for patients with a fixed footplate and unsuccessful previous surgeries or patients who cannot benefit from a stapedotomy for anatomic reasons. In some cases, access to the round window membrane could represent a limitation. However, these promising initial results establish the need for further works with regard to 3 issues: 1) clinical data studies are needed, including a greater number of patients to confirm these preliminary results; 2) a long-term follow-up must be performed to detect any possible cochlear adverse effects, in particular, on the basilar membrane; 3) the effect of fascia interposition and tip size has to be evaluated in experimental studies.