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Heterozygous mutations in the gene PRPF31, encoding a pre-mRNA splicing factor, cause autosomal dominant retinitis pigmentosa (adRP) with reduced penetrance. At the molecular level, pathogenicity results from haploinsufficiency, as the largest majority of such mutations trigger nonsense-mediated mRNA decay or involve large deletions of coding exons. We investigated genetically two families with a history of adRP, one of whom showed incomplete penetrance. All patients underwent thorough ophthalmological examination, including electroretinography (ERG) and Goldmann perimetry. Array-based comparative genomic hybridization (aCGH) and multiplex ligation-dependent probe amplification (MLPA) were used to map heterozygous deletions, while real-time PCR on genomic DNA and long-range PCR allowed resolving the mutations at the base-pair level. PRPF31 transcripts were quantified with real-time PCR on patient-derived lymphoblastoid cell lines. We identified two independent deletions affecting the promoter and the 5' untranslated region (UTR) of PRPF31 but leaving its coding sequence completely unaltered. Analysis of PRPF31 mRNA from lymphoblastoid cell lines from one of these families showed reduced levels of expression in patients versus controls, probably due to the heterozygous ablation of its promoter sequences. In addition to reporting the identification of two novel noncoding deletions in PRPF31, this study provides strong additional evidence that mRNA-mediated haploinsufficiency is the primary cause of pathogenesis for PRPF31-linked adRP.

Achromatopsie ist eine seltene erbliche Erkrankung mit kongenitaler Funktionsstörung der Zapfen. Resultierend daraus, entfällt der Eingang der Zapfen in den visuellen Kortex. Dies wirft die Frage nach Reorganisationsprozessen bei Achromatopsie auf. Wechselwirkungen einer solchen Reorganisation[zum vollständigen Text gelangen Sie über die oben angegebene URL], 27. Jahrestagung der Regionalgesellschaft der Augenärzte Sachsen-Anhalts und Thüringens e. V.

Background The optical accessibility of the eye and technological advances in ophthalmic diagnostics have put ophthalmology at the forefront of data-driven medicine. The focus of this study is rare eye disorders, a group of conditions whose clinical heterogeneity and geographic dispersion make data-driven, evidence-based practice particularly challenging. Inter-institutional collaboration and information sharing is crucial but the lack of standardised terminology poses an important barrier. Ontologies are computational tools that include sets of vocabulary terms arranged in hierarchical structures. They can be used to provide robust terminology standards and to enhance data interoperability. Here, we discuss the development of the ophthalmology-related component of two well-established biomedical ontologies, the Human Phenotype Ontology (HPO; includes signs, symptoms and investigation findings) and the Orphanet Rare Disease Ontology (ORDO; includes rare disease nomenclature/nosology). Methods A variety of approaches were used including automated matching to existing resources and extensive manual curation. To achieve the latter, a study group including clinicians, patient representatives and ontology developers from 17 countries was formed. A broad range of terms was discussed and validated during a dedicated workshop attended by 60 members of the group. Results A comprehensive, structured and well-defined set of terms has been agreed on including 1106 terms relating to ocular phenotypes (HPO) and 1202 terms relating to rare eye disease nomenclature (ORDO). These terms and their relevant annotations can be accessed in http://www.human-phenotype-ontology.org/ and http://www.orpha.net/; comments, corrections, suggestions and requests for new terms can be made through these websites. This is an ongoing, community-driven endeavour and both HPO and ORDO are regularly updated. Conclusions To our knowledge, this is the first effort of such scale to provide terminology standards for the rare eye disease community. We hope that this work will not only improve coding and standardise information exchange in clinical care and research, but also it will catalyse the transition to an evidence-based precision ophthalmology paradigm. Electronic supplementary material The online version of this article (10.1186/s13023-018-0980-6) contains supplementary material, which is available to authorized users.

Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising a two-component system (TCS) and the TCS-regulated iron chelator 2-isocyano-6,7-dihydroxycoumarin (ICDH-Coumarin) that directly senses and modulates environmental ferric iron (Fe3+) availability to determine swarming initiation and biofilm formation. We demonstrate that the two-component system RssA-RssB (RssAB) directly senses environmental ferric iron (Fe3+) and transcriptionally modulates biosynthesis of flagella and the iron chelator ICDH-Coumarin whose production requires the pvc cluster. Addition of Fe3+, or loss of ICDH-Coumarin due to pvc deletion results in prolonged RssAB signaling activation, leading to delayed swarming initiation and increased biofilm formation. We further show that ICDH-Coumarin is able to chelate Fe3+ to switch off RssAB signaling, triggering swarming initiation and biofilm reduction. Our findings reveal a novel cellular system that senses iron levels to regulate bacterial surface lifestyle.

Item does not contain fulltext The majority of the genetic causes of autosomal-recessive (ar) cone-rod dystrophy (CRD) are currently unknown. A combined approach of homozygosity mapping and exome sequencing revealed a homozygous nonsense mutation (c.565C>T [p.Glu189*]) in RAB28 in a German family with three siblings with arCRD. Another homozygous nonsense mutation (c.409C>T [p.Arg137*]) was identified in a family of Moroccan Jewish descent with two siblings affected by arCRD. All five affected individuals presented with hyperpigmentation in the macula, progressive loss of the visual acuity, atrophy of the retinal pigment epithelium, and severely reduced cone and rod responses on the electroretinogram. RAB28 encodes a member of the Rab subfamily of the RAS-related small GTPases. Alternative RNA splicing yields three predicted protein isoforms with alternative C-termini, which are all truncated by the nonsense mutations identified in the arCRD families in this report. Opposed to other Rab GTPases that are generally geranylgeranylated, RAB28 is predicted to be farnesylated. Staining of rat retina showed localization of RAB28 to the basal body and the ciliary rootlet of the photoreceptors. Analogous to the function of other RAB family members, RAB28 might be involved in ciliary transport in photoreceptor cells. This study reveals a crucial role for RAB28 in photoreceptor function and suggests that mutations in other Rab proteins may also be associated with retinal dystrophies.

Contains fulltext : 52374.pdf (Publisher’s version ) (Closed access) Most X-linked diseases show a recessive pattern of inheritance in which female carriers are unaffected. In X-linked retinitis pigmentosa (XLRP), however, both recessive and semi-dominant inheritance patterns have been reported. We identified an Israeli family with semi-dominant XLRP due to a missense mutation (p.G275S) in the RPGR gene. The mutation was previously reported in two Danish families with recessive XLRP. Obligate carriers from the two Danish families had no visual complaints and normal to slightly reduced retinal function, while those from the Israeli family suffered from high myopia, low visual acuity, constricted visual fields, and severely reduced electroretinogram (ERG) amplitudes. The disease-related RPGR haplotype of the Israeli family was found to be different from the one found in the two Danish families, indicating that the mutation arose twice independently on different X-chromosome backgrounds. A series of genetic analyses excluded skewed X-inactivation pattern, chromosomal abnormalities, distorted RPGR expression level, and mutations in candidate genes as the cause for the differences in disease severity of female carriers. To the best of our knowledge, this is the first detailed analysis of an identical mutation causing either a recessive or a semi-dominant X-linked pattern of disease in different families. Our results indicate that an additional gene (or genes), linked to RPGR, modulate disease expression in severely affected carriers. These may be related to the high myopia concomitantly found in affected carriers from the Israeli family.

OBJECTIVE: To investigate the involvement of the Bardet-Biedl syndrome (BBS) gene BBS1 p.M390R variant in nonsyndromic autosomal recessive retinitis pigmentosa (RP). METHODS: Homozygosity mapping of a patient with isolated RP was followed by BBS1 sequence analysis. We performed restriction fragment length polymorphism analysis of the p.M390R allele in 2007 patients with isolated RP or autosomal recessive RP and in 1824 ethnically matched controls. Patients with 2 BBS1 variants underwent extensive clinical and ophthalmologic assessment. RESULTS: In an RP proband who did not fulfill the clinical criteria for BBS, we identified a large homozygous region encompassing the BBS1 gene, which carried the p.M390R variant. In addition, this variant was detected homozygously in 10 RP patients and 1 control, compound heterozygously in 3 patients, and heterozygously in 5 patients and 6 controls. The 14 patients with 2 BBS1 variants showed the entire clinical spectrum, from nonsyndromic RP to full-blown BBS. In 8 of 14 patients, visual acuity was significantly reduced. In patients with electroretinographic responses, a rod-cone pattern of photoreceptor degeneration was observed. CONCLUSIONS: Variants in BBS1 are significantly associated with nonsyndromic autosomal recessive RP and relatively mild forms of BBS. As exemplified in this study by the identification of a homozygous p.M390R variant in a control individual and in unaffected parents of BBS patients in other studies, cis - or trans -acting modifiers may influence the disease phenotype. CLINICAL RELEVANCE: It is important to monitor patients with an early diagnosis of mild BBS phenotypes for possible life-threatening conditions.

Purpose Retinitis pigmentosa (RP), the most genetically heterogeneous disorder in humans, actually represents a group of pigmentary retinopathies characterized by night blindness followed by visual-field loss. RP can appear as either syndromic or nonsyndromic. One of the most common forms of syndromic RP is Usher syndrome, characterized by the combination of RP, hearing loss, and vestibular dysfunction. Methods The underlying cause of the appearance of syndromic and nonsyndromic RP in three siblings from a consanguineous Israeli Muslim Arab family was studied with whole-genome homozygosity mapping followed by whole exome sequencing. Results The family was found to segregate novel mutations of two different genes: myosin VIIA (MYO7A), which causes type 1 Usher syndrome, and phosphodiesterase 6B, cyclic guanosine monophosphate-specific, rod, beta (PDE6B), which causes nonsyndromic RP. One affected child was homozygous for both mutations. Since the retinal phenotype seen in this patient results from overlapping pathologies, one might expect to find severe retinal degeneration. Indeed, he was diagnosed with RP based on an abnormal electroretinogram (ERG) at a young age (9 months). However, this early diagnosis may be biased, as two of his older siblings had already been diagnosed, leading to increased awareness. At the age of 32 months, he had relatively good vision with normal visual fields. Further testing of visual function and structure at different ages in the three siblings is needed to determine whether the two RP-causing genes mutated in this youngest sibling confer increased disease severity. Conclusions This report further supports the genetic heterogeneity of RP, and demonstrates how consanguinity could increase intrafamilial clustering of multiple hereditary diseases. Moreover, this report provides a unique opportunity to study the clinical implications of the coexistence of pathogenic mutations in two RP-causative genes in a human patient.