RESUMEN
BACKGROUND: Alström syndrome is a rare recessively inherited disorder caused by variants in the ALMS1 gene. It is characterized by multiple organ dysfunction, including cone-rod retinal dystrophy, dilated cardiomyopathy, hearing loss, obesity, insulin resistance, hyperinsulinemia, type 2 diabetes mellitus and systemic fibrosis. Heterogeneity and age-dependent development of clinical manifestations make it difficult to obtain a clear diagnosis, especially in pediatric patients. CASE PRESENTATION: Here we report the case of a girl with Alström syndrome. Genetic examination was proposed at age 22 months when suspected macular degeneration was the only major finding. Next generation sequencing of a panel of genes linked to eye-related pathologies revealed two compound heterozygous variants in the ALMS1 gene. Frameshift variants c.1196_1202del, p.(Thr399Lysfs*11), rs761292021 and c.11310_11313del, (p.Glu3771Trpfs*18), rs747272625 were detected in exons 5 and 16, respectively. Both variants cause frameshifts and generation of a premature stop-codon that probably leads to mRNA nonsense-mediated decay. Validation and segregation of ALMS1 variants were confirmed by Sanger sequencing. CONCLUSIONS: Genetic testing makes it possible, even in childhood, to increase the number of correct diagnoses of patients who have ambiguous phenotypes caused by rare genetic variants. The development of high-throughput sequencing technologies offers an exceptionally valuable screening tool for clear genetic diagnoses and ensures early multidisciplinary management and treatment of the emerging symptoms.
Asunto(s)
Síndrome de Alstrom/genética , Proteínas de Ciclo Celular/genética , Diagnóstico Precoz , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Mutación , Síndrome de Alstrom/diagnóstico , Codón sin Sentido , Femenino , Mutación del Sistema de Lectura , Heterocigoto , Humanos , LactanteRESUMEN
PURPOSE: To evaluate, in a pool of affected families, the mutation spectrum in Stargardt patients from Spain, using the ABCR400 microarray that contains described sequence variants in the gene encoding for the photoreceptor specific ATP-binding cassette transporter (ABCA4). METHODS: We analyzed 76 Spanish patients with STGD1 for a population-specific survey on the sequence variations in the ABCA4 gene, using the ABCR400 microarray. RESULTS: Potential disease-associated alleles were identified in 91 of the 152 STGD1 chromosomes studied, resulting in a detection rate of 60%. The two mutant alleles were found in 33/76 patients (43%), whereas in 25/76 cases (33%) only one allele could be identified. In the remaining 18 patients no mutations were found. In total, we identified 40 sequence variations that could be related to the disease. The vast majority of these substitutions (35/40) were missense mutations. Three frameshift mutations and two splicing variants were also found. CONCLUSIONS: We identified a major disease-associated allele, R1129L, which accounted for 24% of the mutated alleles detected, and a high frequency (12%) of complex alleles.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/genética , Análisis Mutacional de ADN , Genes Recesivos , Degeneración Macular/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Alelos , Arginina , ADN Recombinante , Femenino , Mutación del Sistema de Lectura , Variación Genética , Humanos , Leucina , Masculino , Mutación , Mutación Missense , EspañaAsunto(s)
Distrofias Hereditarias de la Córnea/genética , ADN/genética , Microscopía Confocal/métodos , Mutación , Microscopía con Lámpara de Hendidura/métodos , Factor de Crecimiento Transformador beta1/genética , Adulto , Córnea/patología , Distrofias Hereditarias de la Córnea/diagnóstico , Distrofias Hereditarias de la Córnea/metabolismo , Análisis Mutacional de ADN , Humanos , Persona de Mediana Edad , Factor de Crecimiento Transformador beta1/metabolismo , Adulto JovenRESUMEN
Arrays of oligonucleotides synthesized in the 5'-->3' direction have potential benefit in several areas of life sciences research because the free 3'-end can be modified by enzymatic reactions. A Geniom One instrument (febit biomed GmbH, Germany), with integrated chip fabrication, multiplex primer extension, fluorescence imaging, and data analysis, was evaluated for studies of genomic variations. Microchannels used for the array synthesis in Geniom One were not optimized before for the APEX method and, as preliminary experiments demonstrated in this study, the signals were strongly affected by the speed of the process inside reaction channels. Using the two-compartment model (TCM), target binding to feature were quantitatively analyzed, revealing profound mass-transport limitations in the observed kinetics and enabling us to draw a series of physicochemical conclusions of the optimal set-up for the APEX reaction. Some kinetically relevant parameters such as target concentration, reaction time, and temperature were comprehensively analyzed. Finally, we applied the arrays and methods in a proof-of-principle experiment where 36 individuals were typed with 900 oligonucleotide probes (sense and antisense primers for 450 markers), using the ABCR gene as a test system. A new DNA analysis method for studies of genomic variation was developed using this all-in-one platform.