Browsing by Author "Coelho, T"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- LAMA2 Gene Analysis in a Cohort of 26 Congenital Muscular Dystrophy PatientsPublication . Oliveira, J; Santos, R; Soares-Silva, I; Jorge, P; Vieira, E; Oliveira, ME; Moreira, A; Coelho, T; Ferreira, JC; Fonseca, MJ; Barbosa, C; Prats, J; Aríztegui, ML; Martins, ML; Moreno, T; Heinimann, K; Barbot, C; Pascual-Pascual, SI; Cabral, A; Fineza, I; Santos, M; Bronze-da-Rocha, ECongenital muscular dystrophy type 1A (MDC1A) is caused by mutations in the LAMA2 gene encoding laminin-alpha2. We describe the molecular study of 26 patients with clinical presentation, magnetic resonance imaging and/or laminin-alpha2 expression in muscle, compatible with MDC1A. The combination of full genomic sequencing and complementary DNA analysis led to the particularly high mutation detection rate of 96% (50/52 disease alleles). Besides 22 undocumented polymorphisms, 18 different mutations were identified in the course of this work, 14 of which were novel. In particular, we describe the first fully characterized gross deletion in the LAMA2 gene, encompassing exon 56 (c.7750-1713_7899-2153del), detected in 31% of the patients. The only two missense mutations detected were found in heterozygosity with nonsense or truncating mutations in the two patients with the milder clinical presentation and a partial reduction in muscle laminin-alpha2. Our results corroborate the previous few genotype/phenotype correlations in MDC1A and illustrate the importance of screening for gross rearrangements in the LAMA2 gene, which may be underestimated in the literature.
- LAMA2 gene mutation update: Toward a more comprehensive picture of the laminin-α2 variome and its related phenotypesPublication . Oliveira, J; Gruber, A; Cardoso, M; Taipa, R; Fineza, I; Gonçalves, A; Laner, A; Winder, TL; Schroeder, J; Rath, J; Oliveira, ME; Vieira, E; Sousa, AP; Vieira, JP; Lourenço, T; Almendra, L; Negrão, L; Santos, M; Melo-Pires, M; Coelho, T; den Dunnen, JT; Santos, R; Sousa, MCongenital muscular dystrophy type 1A (MDC1A) is one of the main subtypes of early-onset muscle disease, caused by disease-associated variants in the laminin-α2 (LAMA2) gene. MDC1A usually presents as a severe neonatal hypotonia and failure to thrive. Muscle weakness compromises normal motor development, leading to the inability to sit unsupported or to walk independently. The phenotype associated with LAMA2 defects has been expanded to include milder and atypical cases, being now collectively known as LAMA2-related muscular dystrophies (LAMA2-MD). Through an international multicenter collaborative effort, 61 new LAMA2 disease-associated variants were identified in 86 patients, representing the largest number of patients and new disease-causing variants in a single report. The collaborative variant collection was supported by the LOVD-powered LAMA2 gene variant database (https://www.LOVD.nl/LAMA2), updated as part of this work. As of December 2017, the database contains 486 unique LAMA2 variants (309 disease-associated), obtained from direct submissions and literature reports. Database content was systematically reviewed and further insights concerning LAMA2-MD are presented. We focus on the impact of missense changes, especially the c.2461A > C (p.Thr821Pro) variant and its association with late-onset LAMA2-MD. Finally, we report diagnostically challenging cases, highlighting the relevance of modern genetic analysis in the characterization of clinically heterogeneous muscle diseases.
- Screening for Pompe Disease in a Portuguese High Risk PopulationPublication . Almeida, V; Conceição, I; Fineza, I; Coelho, T; Silveira, F; Santos, M; Valverde, A; Geraldo, A; Maré, R; Aguiar, TC; Mendonça, C; Martins, J; Medeiros, L; Barroso, C; Vieira, JP; Moreno, T; Negrão, L; Silva Dias, M; Lacerda, L; Evangelista, TPompe disease is a rare metabolic disorder with available enzymatic replacement therapy. Contrasting with the classic infantile form, the others subtypes have a heterogeneous presentation that makes an early and accurate diagnosis difficult. We conducted a prospective, multicenter, observational study to identify undiagnosed patients. During a one-year period, patients followed in Portuguese neuromuscular outpatient clinics with proximal muscle weakness affecting upper and/or lower limbs, hyperCKemia in two or more determinations or hypotonia and hyperCKemia, were screened for acid α-glucosidase deficiency by dried blood spots. Lysosomal acid-alpha-1,4-glucosidase activity was determined by tandem mass spectrometry and positive results were confirmed by molecular study. From the 99 patients screened, Pompe disease was confirmed in 4, with age of onset ranging from 2.5 to 48 years, all with limb girdle muscle weakness, corresponding to a frequency of 4% in our cohort and 4.9% of limb girdle muscle weakness. Screening for Pompe disease in high risk populations, using dried blood spots, was already performed in some European populations. Apart from two negative Scandinavian studies, positive cases were confirmed in 2.8-7.9% of patients presenting with limb girdle muscle weakness and in 0-2.5% with isolated hyperCKemia.