Browsing by Author "Viana-Baptista, M."
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- Kalirin: a novel genetic risk factor for ischemic strokePublication . Krug, T.; Manso, H.; Gouveia, L.; Sobral, J.; Xavier, J.M.; Albergaria, I.; Gaspar, G.; Correia, M.; Viana-Baptista, M.; Simões, R.M.; Pinto, A.N.; Taipa, R.; Ferreira, C.; Fontes, J.R.; Silva, M.R.; Gabriel, J.P.; Matos, I.; Lopes, G.; Ferro, J.M.; Vicente, A.M.; Oliveira, S.A.Cerebrovascular and cardiovascular diseases are the leading causes of death and disability worldwide. They are complex disorders resulting from the interplay of genetic and environmental factors, and may share several susceptibility genes. Several recent studies have implicated variants of the Kalirin (KALRN) gene with susceptibility to cardiovascular and metabolic phenotypes, but no studies have yet been performed in stroke patients. KALRN is involved, among others, in the inhibition of inducible nitric oxide synthase, in the regulation of ischemic signal transduction, and in neuronal morphogenesis, plasticity, and stability. The goal of the present study was to determine whether SNPs in the KALRN region on 3q13, which includes the Ropporin gene (ROPN1), predispose to ischemic stroke (IS) in a cohort of Portuguese patients and controls. We genotyped 34 tagging SNPs in the KALRN and ROPN1 chromosomal region on 565 IS patients and 517 unrelated controls, and performed genotype imputation for 405 markers on chromosome 3. We tested the single-marker association of these SNPs with IS. One SNP (rs4499545) in the ROPN1-KALRN intergenic region and two SNPs in KALRN (rs17286604 and rs11712619) showed significant (P < 0.05) allelic and genotypic (unadjusted and adjusted for hypertension, diabetes, and ever smoking) association with IS risk. Thirty-two imputed SNPs also showed an association at P < 0.05, and actual genotyping of three of these polymorphisms (rs7620580, rs6438833, and rs11712039) validated their association. Furthermore, rs11712039 was associated with IS (0.001 < P < 0.01) in a recent well-powered genomewide association study (Ikram et al. 2009). These studies suggest that variants in the KALRN gene region constitute risk factors for stroke and that KALRN may represent a common risk factor for vascular diseases.
- Mitochondrial haplogroup H1 is protective for ischemic stroke in Portuguese patientsPublication . Rosa, A.; Fonseca, B.V.; Krug, T.; Manso, H.; Gouveia, L.; Albergaria, I.; Gaspar, G.; Correia, M.; Viana-Baptista, M.; Simões, R.M.; Pinto, A.N.; Taipa, R.; Ferreira, C.; Fontes, J.R.; Silva, M.R.; Gabriel, J.P.; Matos, I.; Lopes, G.; Ferro, J.M.; Vicente, A.M.; Oliveira, S.A.The genetic contribution to stroke is well established but it has proven difficult to identify the genes and the disease-associated alleles mediating this effect, possibly because only nuclear genes have been intensely investigated so far. Mitochondrial DNA (mtDNA) has been implicated in several disorders having stroke as one of its clinical manifestations. The aim of this case-control study was to assess the contribution of mtDNA polymorphisms and haplogroups to ischemic stroke risk.
- The alpha-galactosidase A p.Arg118Cys variant does not cause a Fabry disease phenotype: data from individual patients and family studiesPublication . Ferreira, S.; Ortiz, A.; Germain, D.P.; Viana-Baptista, M.; Caldeira-Gomes, A.; Camprecios, M.; Fenollar-Cortés., M; Gallegos-Villalobos, Á.; Garcia, D.; García-Robles, J.A.; Egido, J.; Gutiérrez-Rivas, E.; Herrero, J.A.; Mas, S.; Oancea, R.; Péres, P.; Salazar-Martín, L.M.; Solera-Garcia, J.; Alves, H.; Garman, S.C.; Oliveira, J.P.Lysosomal α-galactosidase A (α-Gal) is the enzyme deficient in Fabry disease (FD), an X-linked glycosphingolipidosis caused by pathogenic mutations affecting the GLA gene. The early-onset, multi-systemic FD classical phenotype is associated with absent or severe enzyme deficiency, as measured by in vitro assays, but patients with higher levels of residual α-Gal activity may have later-onset, more organ-restricted clinical presentations. A change in the codon 118 of the wild-type α-Gal sequence, replacing basic arginine by a potentially sulfhydryl-binding cysteine residue - GLA p.(Arg118Cys) -, has been recurrently described in large FD screening studies of high-risk patients. Although the Cys118 allele is associated with high residual α-Gal activity in vitro, it has been classified as a pathogenic mutation, mainly on the basis of theoretical arguments about the chemistry of the cysteine residue. However its pathogenicity has never been convincingly demonstrated by pathology criteria. We reviewed the clinical, biochemical and histopathology data obtained from 22 individuals of Portuguese and Spanish ancestry carrying the Cys118 allele, including 3 homozygous females. Cases were identified either on the differential diagnosis of possible FD manifestations and on case-finding studies (n=11; 4 males), or on unbiased cascade screening of probands' close relatives (n=11; 3 males). Overall, those data strongly suggest that the GLA p.(Arg118Cys) variant does not segregate with FD clinical phenotypes in a Mendelian fashion, but might be a modulator of the multifactorial risk of cerebrovascular disease. The Cys118 allelic frequency in healthy Portuguese adults (n=696) has been estimated as 0.001, therefore not qualifying for "rare" condition.