Browsing by Author "Coelho, Teresa"
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- Bases moleculares de los defectos en el complejo mitocondrial ETF/ETF-QOPublication . Rocha, Hugo; Nogueira, Célia; Martins, Esmeralda; Rodrigues, Esmeralda; Leão, Miguel; Sousa, Carmen; Fonseca, Helena; Marcão, Ana; Gaspar, Ana; Brandão, Otilia; Santos, Helena; Coelho, Teresa; Ribeiro, J. Miguel; Vilarinho, LauraDefectos en el complejo mitocondrial ETF/ETF-QO (ETF - flavoproteína transferidora de electrones; ETFQO - flavoproteína transferidora de electrones ubiquinona oxidorreductasa), resultan en la disfunción secundaria de 11 deshidrogenasas que utilizan este complejo para transferir los electrones a la cadena de transporte electrónico, bloqueando la β-oxidación de los ácidos grasos, de aminoácidos y de la colina. Defectos en el funcionamiento del complejo resultan en una deficiencia multiple de acil-CoA deshidrogenasas (MADD; aciduria glutárica tipo II; OMIM 231680) que representa un grupo muy heterogéneo de enfermedades metabólicas tanto desde el punto de vista clínico como molecular. Pueden tener como causa mutaciones en los genes que codifican para las subunidades del complejo (ETFA, ETFB y ETFDH), genes que codifican los transportadores de riboflavina, del transporte ó de la síntesis del FAD. Bioquímicamente, las MADD se caracterizan por la acumulación de acilcarnitinas de cadena corta, media y larga, siendo su detección la abordaje primaria al diagnóstico, incluso en cribado neonatal. La multiplicidad de defectos genéticos que pueden cursar por una disfunción del complejo ETF/ETF-QO (creyéndose que siguen sin estar identificados todos), el hecho de que no siempre están presentes los marcadores bioquímicos evidentes (acumulación de las acilcarnitinas características) y la grande variabilidad clínica son factores que conducen a una dificultad aumentada en de diagnóstico de este grupo de errores congénitos del metabolismo. En este panorama el conocimiento de la epidemiologia molecular es fundamental. Los autores presentaran las bases moleculares de los trastornos en el funcionamiento del complejo ETF/ETF-QO en Portugal.
- McArdle disease: mutational spectrum of Portuguese patientsPublication . Rocha, Hugo; Lopes, Altina; Soares, Gabriela; Negrão, Luis; Coelho, Teresa; Chorão, Rui; Lourenço, Teresa; Vilarinho, LauraMcArdle disease or Glycogen Storage Disease type V (GSD V; myophosphorylase deficiency; MIM 232600) its an inborn error of glycogen metabolism, caused by a deficiency in muscle specific isoform of glycogen phosphorylase. This metabolic myopathy is characterised by exercise intolerance, myalgia, cramps and episodic myoglobinuria, symptoms that usually appear during the second or third decade of life. The diagnosis was typically made in muscle biopsy by histological analysis (demonstration of subsarcolemmal glycogen deposits and negative histochemical stain for phosphorylase) and/or measurement of muscle phosphorylase activity. Although since 1984, when the gene of muscle isoform of phosphorylase (myophosphorylase) was cloned and assigned to chromosome 11 (11q13), molecular genetics analysis has been more and more used to confirm the clinical diagnosis. Until now, 146 pathogenic mutations have been described (according to HGMDTM) including nonsense, missense and framshift mutations. High genetic heterogeneity is a hallmark of McArdle disease with a very frequent common mutation among Caucasian populations – R49X (present in about 60% of the mutated alleles) – and several rare mutations, without a clear genotype/phenotype correlation. The authors will present molecular data from the characterisation of 53 Portuguese patients, from 42 families, with McArdle disease. Our results reveal the presence of the R49X mutation in 60 of the alleles (57%), in accordance to what has been described to other Caucasian populations, being identified a total of 15 different mutations were identified. These results allowed in many cases the diagnosis without the need of a muscle biopsy, but also provide valuable information for genetic counselling and to increase the knowledge about the molecular pathology of this disorder.
- Private dysferlin exon skipping mutation (c.5492G>A) with a founder effect reveals further alternative splicing involving exons 49-51Publication . Santos, Rosário; Oliveira, Jorge; Vieira, Emília; Coelho, Teresa; Carneiro, António Leite; Evangelista, Teresinha; Dias, Cristina; Fortuna, Ana; Geraldo, Argemiro; Negrão, Luís; Guimarães, António; Bronze-da-Rocha, ElsaThe allelic muscle disorders known as limb-girdle muscular dystrophy type 2B (LGMD2B), Miyoshi myopathy and distal anterior compartment myopathy result from defects in dysferlin—a sarcolemma-associated protein involved in membrane repair. Mutation screening in the dysferlin gene (DYSF) enabled the identification of seven Portuguese patients presenting the variant c.5492G4A, which was observed to promote skipping of exon 49 (p.Gly1802ValfsX17). Several residually expressed products of alternative splicing also involving exons 50 and 51 were detected in the leukocytes and muscle of both patients and normal controls. Quantitative transcript analysis confirmed these results and revealed that D49/D50 transcripts were predominant in blood. Although the patients were apparently unrelated, the c.5492G4A mutation was found in linkage disequilibrium with a particularly rare haplotype in the population, corroborating the hypothesis of a common origin. Despite the presence of the same mutation on the same haplotype background, onset of the disease was heterogeneous, with either proximal or distal muscle involvement.