OSBPL2 encodes a protein of inner and outer hair cell stereocilia and is mutated in autosomal dominant hearing loss (DFNA67).

Background: Early-onset hearing loss is mostly of genetic origin. The complexity of the hearing process is reflected by its extensive genetic heterogeneity, with probably many causative genes remaining to be identified. Here, we aimed at identifying the genetic basis for autosomal dominant non-syndromic hearing loss (ADNSHL) in a large German family.

Non-manifesting AHI1 truncations indicate localized loss-of-function tolerance in a severe Mendelian disease gene.

Determination of variant pathogenicity represents a major challenge in the era of high-throughput sequencing. Erroneous categorization may result if variants affect genes that are in fact dispensable. We demonstrate that this also applies to rare, apparently unambiguous truncating mutations of an established disease gene.

Autosomal dominant SCA5 and autosomal recessive infantile SCA are allelic conditions resulting from SPTBN2 mutations.

Although many genes have been identified for the autosomal recessive cerebellar ataxias (ARCAs), several patients are unlinked to the respective loci, suggesting further genetic heterogeneity. We combined homozygosity mapping and exome sequencing in a consanguineous Egyptian family with congenital ARCA, mental retardation and pyramidal signs. A homozygous 5-bp deletion in SPTBN2, the gene whose in-frame mutations cause autosomal dominant spinocerebellar ataxia type 5, was shown to segregate with ataxia in the family.

Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice.

The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins-myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans-do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards.

Targeted next-generation sequencing identifies a homozygous nonsense mutation in ABHD12, the gene underlying PHARC, in a family clinically diagnosed with Usher syndrome type 3.

Background: Usher syndrome (USH) is an autosomal recessive genetically heterogeneous disorder with congenital sensorineural hearing impairment and retinitis pigmentosa (RP). We have identified a consanguineous Lebanese family with two affected members displaying progressive hearing loss, RP and cataracts, therefore clinically diagnosed as USH type 3 (USH3). Our study was aimed at the identification of the causative mutation in this USH3-like family.

Mutations in KIF7 link Joubert syndrome with Sonic Hedgehog signaling and microtubule dynamics.

Joubert syndrome (JBTS) is characterized by a specific brain malformation with various additional pathologies. It results from mutations in any one of at least 10 different genes, including NPHP1, which encodes nephrocystin-1. JBTS has been linked to dysfunction of primary cilia, since the gene products known to be associated with the disorder localize to this evolutionarily ancient organelle.

PDZD7 is a modifier of retinal disease and a contributor to digenic Usher syndrome.

Usher syndrome is a genetically heterogeneous recessive disease characterized by hearing loss and retinitis pigmentosa (RP). It frequently presents with unexplained, often intrafamilial, variability of the visual phenotype. Although 9 genes have been linked with Usher syndrome, many patients do not have mutations in any of these genes, suggesting that there are still unidentified genes involved in the syndrome.

Sequence variants of the DFNB31 gene among Usher syndrome patients of diverse origin.

Purpose: It has been demonstrated that mutations in deafness, autosomal recessive 31 (DFNB31), the gene encoding whirlin, is responsible for nonsyndromic hearing loss (NSHL; DFNB31) and Usher syndrome type II (USH2D). We screened DFNB31 in a large cohort of patients with different clinical subtypes of Usher syndrome (USH) to determine the prevalence of DFNB31 mutations among USH patients.

Methods: DFNB31 was screened in 149 USH2, 29 USH1, six atypical USH, and 11 unclassified USH patients from diverse ethnic backgrounds.

A novel VPS13B mutation in two brothers with Cohen syndrome, cutis verticis gyrata and sensorineural deafness.

We have earlier described a syndrome characterized by microcephaly, cutis verticis gyrata, retinitis pigmentosa, cataracts, hearing loss and mental retardation (Mendelian inheritance in man (MIM) no: 605685) in two brothers from a non-consanguineous Lebanese family. In view of the rarity of the disorder and the high rate of inbreeding in the Lebanese population, we assumed an autosomal recessive trait inherited from a common ancestor. A genomewide scan was performed.

An USH2A founder mutation is the major cause of Usher syndrome type 2 in Canadians of French origin and confirms common roots of Quebecois and Acadians.

Congenital hearing loss affects approximately one child in 1000. About 10% of the deaf population have Usher syndrome (USH). In USH, hearing loss is complicated by retinal degeneration with onset in the first (USH1) or second (USH2) decade.

Usher syndrome type 1 due to missense mutations on both CDH23 alleles: investigation of mRNA splicing.

Usher syndrome (USH) is an autosomal recessive condition characterized by sensorineural hearing loss, vestibular dysfunction, and visual impairment due to retinitis pigmentosa. Truncating mutations in the cadherin-23 gene (CDH23) result in Usher syndrome type 1D (USH1D), whereas missense mutations affecting strongly conserved motifs of the CDH23 protein cause non-syndromic deafness (DFNB12). Four missense mutations constitute an exception from this genotype-phenotype correlation: they have been described in USH1 patients in homozygous state.

Two truncating USH3A mutations, including one novel, in a German family with Usher syndrome.

Purpose: To identify the genetic defect in a German family with Usher syndrome (USH) and linkage to the USH3A locus.

Methods: DNA samples of five family members (both parents and the three patients) were genotyped with polymorphic microsatellite markers specific for eight USH genes. Three affected family members underwent detailed ocular and audiologic characterization.

Deafblindness in French Canadians from Quebec: a predominant founder mutation in the USH1C gene provides the first genetic link with the Acadian population.

Background: Usher syndrome type 1 (USH1) is the leading cause of deafblindness. In most populations, many private mutations are distributed across the five known USH1 genes. We investigated patients from the French Canadian population of Quebec (approximately 6 million people) that descends from about 8,500 French settlers who colonized the St Lawrence River valley between 1608 and 1759.

Truncating mutation of the DFNB59 gene causes cochlear hearing impairment and central vestibular dysfunction.

We have identified a consanguineous family from Morocco segregating autosomal recessive congenital progressive hearing loss (ARNSHL) and retinal degeneration. Detailed clinical investigation of the six siblings revealed combined severe cone-rod dystrophy (CORD) and severe/profound hearing impairment in two of them, while there is isolated CORD in three and nonsyndromic profound hearing loss in one. We therefore assumed a partial overlap of two nonsyndromic autosomal recessive conditions instead of a monogenic syndrome and performed genomewide linkage analysis.

A novel gene for Usher syndrome type 2: mutations in the long isoform of whirlin are associated with retinitis pigmentosa and sensorineural hearing loss.

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.

Protocadherin-21 (PCDH21), a candidate gene for human retinal dystrophies.

Purpose: It has been demonstrated that mice lacking a functional copy of prCAD, the gene encoding protocadherin-21, show progressive photoreceptor degeneration. Therefore we searched for a human retinal phenotype associated with mutations in the orthologous human gene, PCDH21.

Methods: We characterized the genomic organization of human PCDH21 and performed mutation screening in 224 patients with autosomal recessive retinitis pigmentosa, 29 patients with Leber congenital amaurosis, and 26 patients with Usher syndrome type 1.