Browsing by Author "Oliveira, CR"
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- Analysis of Parkinson disease patients from Portugal for mutations in SNCA, PRKN, PINK1 and LRRK2.Publication . Brás, JM; Guerreiro, RJ; Morgadinho, A; Januário, C; Dias, M; Calado, A; Semedo, C; Oliveira, CR; Hardy, J; Singleton, ABACKGROUND: Mutations in the genes PRKN and LRRK2 are the most frequent known genetic lesions among Parkinson's disease patients. We have previously reported that in the Portuguese population the LRRK2 c.6055G > A; p.G2019S mutation has one of the highest frequencies in Europe. METHODS: Here, we follow up on those results, screening not only LRRK2, but also PRKN, SNCA and PINK1 in a cohort of early-onset and late-onset familial Portuguese Parkinson disease patients. This series comprises 66 patients selected from a consecutive series of 132 patients. This selection was made in order to include only early onset patients (age at onset below 50 years) or late-onset patients with a positive family history (at least one affected relative). All genes were sequenced bi-directionally, and, additionally, SNCA, PRKN and PINK1 were subjected to gene dosage analysis. RESULTS: We found mutations both in LRRK2 and PRKN, while the remaining genes yielded no mutations. Seven of the studied patients showed pathogenic mutations, in homozygosity or compound heterozygosity for PRKN, and heterozygosity for LRRK2. CONCLUSION: Mutations are common in Portuguese patients with Parkinson's disease, and these results clearly have implications not only for the genetic diagnosis, but also for the genetic counseling of these patients.
- Apolipoprotein E epsilon4 allele is a risk factor for Alzheimer's disease: the central region of portugal (Coimbra) as a case studyPublication . Fernandes, MA; Oliveira, CR; Oliveira, LM; Nogueira, AJ; Santiago, B; Santana, I
- Association of HFE common mutations with Parkinson's disease, Alzheimer's disease and mild cognitive impairment in a Portuguese cohort.Publication . Guerreiro, RJ; Brás, JM; Santana, I; Januário, C; Morgadinho, A; Ribeiro, MH; Hardy, J; Singleton, A; Oliveira, CRBACKGROUND: Pathological brain iron deposition has been implicated as a source of neurotoxic reactive oxygen species in Alzheimer (AD) and Parkinson diseases (PD). Iron metabolism is associated with the gene hemochromatosis (HFE Human genome nomenclature committee ID:4886), and mutations in HFE are a cause of the iron mismetabolism disease, hemochromatosis. Several reports have tested the association of HFE variants with neurodegenerative diseases, such as AD and PD with conflicting results. METHODS: Genotypes were analysed for the two most common variants of HFE in a series of 130 AD, 55 Mild Cognitive Impairment (MCI) and 132 PD patients. Additionally, a series of 115 healthy age-matched controls was also screened. RESULTS: A statistically significant association was found in the PD group when compared to controls, showing that the presence of the C282Y variant allele may confer higher risk for developing the disease. CONCLUSION: Taken together these results suggest that the common variants in HFE may be a risk factor for PD, but not for AD in the Portuguese population.
- Bioenergetic dysfunction in Huntington's disease human cybridsPublication . Ferreira, IL; Cunha-Oliveira, T; Nascimento, MV; Ribeiro, M; Proença, MT; Januário, C; Oliveira, CR; Rego, ACIn this work we studied the mitochondrial-associated metabolic pathways in Huntington's disease (HD) versus control (CTR) cybrids, a cell model in which the contribution of mitochondrial defects from patients is isolated. HD cybrids exhibited an interesting increase in ATP levels, when compared to CTR cybrids. Concomitantly, we observed increased glycolytic rate in HD cybrids, as revealed by increased lactate/pyruvate ratio, which was reverted after inhibition of glycolysis. A decrease in glucose-6-phosphate dehydrogenase activity in HD cybrids further indicated decreased rate of the pentose-phosphate pathway. ATP levels of HD cybrids were significantly decreased under glycolysis inhibition, which was accompanied by a decrease in phosphocreatine. Nevertheless, pyruvate supplementation could not recover HD cybrids' ATP or phosphocreatine levels, suggesting a dysfunction in mitochondrial use of that substrate. Oligomycin also caused a decrease in ATP levels, suggesting a partial support of ATP generation by the mitochondria. Nevertheless, mitochondrial NADH/NAD(t) levels were decreased in HD cybrids, which was correlated with a decrease in pyruvate dehydrogenase activity and protein expression, suggesting decreased tricarboxylic acid cycle (TCA) input from glycolysis. Interestingly, the activity of alpha-ketoglutarate dehydrogenase, a critical enzyme complex that links the TCA to amino acid synthesis and degradation, was increased in HD cybrids. In accordance, mitochondrial levels of glutamate were increased and alanine was decreased, whereas aspartate and glutamine levels were unchanged in HD cybrids. Conversely, malate dehydrogenase activity from total cell extracts was unchanged in HD cybrids. Our results suggest that inherent dysfunction of mitochondria from HD patients affects cellular bioenergetics in an otherwise functional nuclear background.
- Complete screening for glucocerebrosidase mutations in Parkinson disease patients from PortugalPublication . Brás, JM; Paisan-Ruiz, C; Guerreiro, C; Ribeiro, MH; Morgadinho, A; Januário, C; Sidransky, E; Oliveira, CR; Singleton, AMutations in the gene encoding beta-glucocerebrosidase, a lysosomal degrading enzyme, have recently been associated with the development of Parkinson disease. Here we report the results found in a cohort of Portuguese Parkinson disease patients and healthy age-matched controls for mutations in the aforementioned gene. This screening was accomplished by sequencing the complete open-reading frame, as well as intron/exon boundaries, of the glucocerebrosidase gene, in a total of 230 patients and 430 controls. We have found an increased number of Parkinson disease patients presenting mutations in GBA when compared to controls. These results, together with recent literature, clearly suggest a role of glucocerebrosidase in the development of Parkinson disease.
- Diagnostic value of CSF protein profile in a Portuguese population of sCJD patientsPublication . Baldeiras, IE; Ribeiro, MH; Pacheco, P; Machado, A; Santana, I; Cunha, L; Oliveira, CRThe clinical diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) is difficult, and reliable markers are highly desired. In this work we assess the value of several cerebrospinal fluid (CSF) markers for sCJD diagnosis. Within the framework of the Portuguese Epidemiological Surveillance Program for Human Prion Diseases, CSF samples from 71 patients with clinically suspected sCJD, 30 definite sCJD and 41 non-CJD patients, were analysed for the presence of 14-3-3 protein. CSF levels of tau (t-tau), and phosphorylated tau (p-tau181), S-100b and beta amyloid (Abeta42) proteins were determined. The influence of clinical and genetic characteristics on CSF markers sensitivity was also evaluated. Protein 14-3-3 was detected in 29/30 sCJD patients and 9/41 non-CJD patients. Extremely elevated t-tau and S-100b protein levels were found in sCJD patients, while p-tau181 levels were only slightly elevated and Abeta42 showed no differences compared to controls. 14-3-3 was the most sensitive parameter (97%), but its specificity was low (78%); sensitivity/specificity for other proteins were: S-100b-93/93%, t-tau-93/95%, with maximum accuracy being obtained by a combination of tests (14-3-3 combined with either t-tau or S-100b, or combining S-100b with t-tau/Abeta42 or p-tau/t-tau ratios). The sensitivity of 14-3-3, as well as of p-tau181/t-tau ratio, was decreased in younger patients with long disease duration, with the PrP-2 isotype and MV genotype. Both 14-3-3, t-tau and S-100b are sensitive markers for sCJD, but 14-3-3 specificity seems to be lower in this special clinical setting of rapidly progressing dementias. We propose that in cases with a 14-3-3 weak positive result, or in young patients with long disease duration, a second CSF marker would be valuable for the diagnosis of sCJD.
- Encefalite do tronco e mielite por listeria num jovem adulto previamente saudávelPublication . Bento, C; Januário, C; Silva, S; Oliveira, CR
- Estudo do perfil do envelhecimento da população portuguesaPublication . Oliveira, CR; Santos-Rosa, M; Mota-Pinto, A; Botelho, MA; Morais, A; Veríssimo, MT
- Frontotemporal dementia and mitochondrial DNA transitionsPublication . Grazina, M; Silva, F; Santana, I; Santiago, B; Mendes, C; Simões, M; Oliveira, M; Cunha, L; Oliveira, CRFrontotemporal dementia (FTD) is the second most common type of primary degenerative dementia. Some patients present an overlap between Alzheimer's disease (AD) and FTD both in neuropathological and clinical aspects. This may suggest a similar overlap in physiopathology, namely an involvement of mitochondrial DNA (mtDNA) in FTD, as it has been associated to AD. To determine if mtDNA is involved in FTD, we performed a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analysis, specific to mtDNA NADH Dehydrogenase subunit 1 (ND1) nucleotides 3337-3340, searching for mutations previously described in Parkinson's and AD patients. We could identify one FTD patient with two mtDNA transitions: one already known (3316 G-to-A) and another unreported (3337 G-to-A). Additionally, mitochondrial respiratory chain complex I activity was reduced in leukocytes of this patient (36% of the control mean activity). To our knowledge, this is the first report of mtDNA variants in FTD patients.
- G2019S dardarin substitution is a common cause of Parkinson's disease in a Portuguese cohort.Publication . Brás, JM; Guerreiro, RJ; Ribeiro, MH; Januário, C; Morgadinho, A; Oliveira, CR; Hardy, J; Singleton, ALRRK2 mutations have recently been described in families with Parkinson's disease. Here we show that one of them (G2019S) is present in 6% (7 of 124) unrelated cases of disease in a clinic-based sample series from central Portugal, but not present in 126 controls from the same population. Thus, LRRK2 mutations appear to be a common cause of typical Parkinson's disease and as such will alter clinical practice.