RESUMEN
We describe a kindred with slowly progressive gastrointestinal symptoms and autonomic neuropathy caused by autosomal dominant, hereditary systemic amyloidosis. The amyloid consists of Asp76Asn variant ß(2)-microglobulin. Unlike patients with dialysis-related amyloidosis caused by sustained high plasma concentrations of wild-type ß(2)-microglobulin, the affected members of this kindred had normal renal function and normal circulating ß(2)-microglobulin values. The Asp76Asn ß(2)-microglobulin variant was thermodynamically unstable and remarkably fibrillogenic in vitro under physiological conditions. Previous studies of ß(2)-microglobulin aggregation have not shown such amyloidogenicity for single-residue substitutions. Comprehensive biophysical characterization of the ß(2)-microglobulin variant, including its 1.40-Å, three-dimensional structure, should allow further elucidation of fibrillogenesis and protein misfolding.
Asunto(s)
Amiloidosis Familiar/genética , Microglobulina beta-2/genética , Amiloidosis Familiar/complicaciones , Diarrea/etiología , Femenino , Genes Dominantes , Humanos , Masculino , Persona de Mediana Edad , Linaje , Estructura Cuaternaria de Proteína , Proteoma/genética , Síndrome de Sjögren/complicaciones , Síndrome de Sjögren/genética , Microglobulina beta-2/químicaRESUMEN
PURPOSE: To report the clinical and molecular findings of a kindred with Wagner syndrome (WS) revealed by intraocular inflammatory features. METHODS: Eight available family members underwent complete ophthalmologic examination, including laser flare cell meter measurements. Collagen, type II, alpha 1, versican (VCAN), frizzled family receptor 4, low density lipoprotein receptor-related protein 5, tetraspanin 12, and Norrie disease (pseudoglioma) genes were screened with direct sequencing. RESULTS: The index case was initially referred for unexplained severe and chronic postoperative bilateral uveitis following a standard cataract surgery procedure. Clinical examination of the proband revealed an optically empty vitreous with avascular vitreous strands and veils, features highly suggestive of WS. The systematic familial ophthalmologic examination identified three additional unsuspected affected family members who also presented with the WS phenotype, including uveitis for one of them. We identified a novel c.4004-6T>A nucleotide substitution at the acceptor splice site of intron 7 of the VCAN gene that segregated with the disease phenotype. CONCLUSIONS: We present a family with WS with typical WS features and intraocular inflammatory manifestations associated with a novel splice site VCAN mutation. Beyond the structural role in the retinal-vitreous architecture, versican is also emerging as a pivotal mediator of the inflammatory response, supporting uveitis predisposition as a clinical manifestation of WS.
Asunto(s)
Mutación/genética , Degeneración Retiniana/complicaciones , Degeneración Retiniana/genética , Uveítis/complicaciones , Uveítis/genética , Versicanos/deficiencia , Adolescente , Adulto , Anciano , Secuencia de Bases , Simulación por Computador , Familia , Femenino , Fondo de Ojo , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Fenotipo , Procesamiento Postranscripcional del ARN/genética , Sitios de Empalme de ARN/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Versicanos/genética , Adulto JovenRESUMEN
PURPOSE: Investigate the genotype-phenotype correlations for five TGFBI (transforming growth factor, beta-induced) mutations including one novel pathogenic variant and one complex allele affecting the fourth FAS1 domain of keratoepithelin, and their potential effects on the protein's structure. METHODS: Three unrelated families were clinically diagnosed with lattice corneal dystrophy (CD) and one with an unclassified CD of Bowman's layer. Mutations in the TGFBI gene were detected by direct sequencing, and the functional impact of each variant was predicted using in silico algorithms. Corneal phenotypes, including histological examinations, were compared with the literature data. Furthermore, molecular modeling studies of these mutations were performed. RESULTS: Two distinct missense mutations affecting the same residue at position 509 of keratoepithelin: p.Leu509Pro (c.1526T>C) and p.Leu509Arg (c.1526T>G) were found to be associated with a lattice-type CD. The novel p.Val613Gly (c.1828T>G) TGFBI mutation was found in a sporadic case of an Algerian individual affected by lattice CD. Finally, the Bowman's layer CD was linked to the association in cis of the p.Met502Val and p.Arg555Gln variants, leading to the reclassification of this CD as atypical Thiel-Behnke CD. Structural modeling of these TGFBI mutations argues in favor of these mutations being responsible for instability and/or incorrect folding of keratoepithelin, predictions that are compatible with the clinical diagnoses. CONCLUSIONS: Description of a novel TGFBI mutation and a complex TGFBI allele further extends the mutational spectrum of TGFBI. Moreover, we show convincing evidence that TGFBI mutations affecting Leu509 are linked to the lattice phenotype in two unrelated French families, contrasting with findings previously reported. The p.Leu509Pro was reported to be associated with both amyloid and non-amyloid aggregates, whereas p.Leu509Arg has been described as being responsible for Epithelial Basement Membrane Dystrophy (EBMD).
Asunto(s)
Lámina Limitante Anterior/metabolismo , Distrofias Hereditarias de la Córnea/genética , Proteínas de la Matriz Extracelular/genética , Factor de Crecimiento Transformador beta/genética , Adulto , Anciano de 80 o más Años , Argelia/etnología , Alelos , Secuencia de Aminoácidos , Lámina Limitante Anterior/patología , Distrofias Hereditarias de la Córnea/clasificación , Distrofias Hereditarias de la Córnea/epidemiología , Distrofias Hereditarias de la Córnea/etnología , Distrofias Hereditarias de la Córnea/patología , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Francia/epidemiología , Frecuencia de los Genes , Estudios de Asociación Genética , Ligamiento Genético , Genotipo , Humanos , Lactante , Masculino , Persona de Mediana Edad , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Linaje , Fenotipo , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
The frequency of disease-related large rearrangements (referred to as copy-number mutations, CNMs) varies among genes, and search for these mutations has an important place in diagnostic strategies. In recent years, CGH method using custom-designed high-density oligonucleotide-based arrays allowed the development of a powerful tool for detection of alterations at the level of exons and made it possible to provide flexibility through the possibility of modeling chips. The aim of our study was to test custom-designed oligonucleotide CGH array in a diagnostic laboratory setting that analyses several genes involved in various genetic diseases, and to compare it with conventional strategies. To this end, we designed a 12-plex CGH array (135k; 135 000 probes/subarray) (Roche Nimblegen) with exonic and intronic oligonucleotide probes covering 26 genes routinely analyzed in the laboratory. We tested control samples with known CNMs and patients for whom genetic causes underlying their disorders were unknown. The contribution of this technique is undeniable. Indeed, it appeared reproducible, reliable and sensitive enough to detect heterozygous single-exon deletions or duplications, complex rearrangements and somatic mosaicism. In addition, it improves reliability of CNM detection and allows determination of boundaries precisely enough to direct targeted sequencing of breakpoints. All of these points, associated with the possibility of a simultaneous analysis of several genes and scalability 'homemade' make it a valuable tool as a new diagnostic approach of CNMs.