SN - Serviço de Neurologia
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Browsing SN - Serviço de Neurologia by Author "Alonso, I."
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- Assessing risk factors for migraine: differences in gender transmissionPublication . Lemos, C.; Alonso, I.; Barros, J.; Sequeiros, J.; Pereira-Monteiro, J.; Mendonça, D.; Sousa, A.Abstract AIM: Our aim was to assess which specific factors are contributing to an increased risk of migraine in a group of 131 Portuguese families. METHODS: We studied 319 first-degree relatives, using a multilevel approach to account for the dependency among members from the same family. We included in the model relative's gender, the proband's gender and age-at-onset, to evaluate if any of these variables were associated with relative's affection status. We also included in the model proband's migraine subtype. We further assessed female and male transmissions within the proband nuclear family. RESULTS: Relatives' gender was found to be a risk factor for migraine (Odds Ratio = 2.86; 95% CI = 1.75-4.67), with females at a higher risk. When splitting probands according to their migraine subtype, we found that none of the variables studied contributed to relatives of MA-probands affection-status. Our results also show a significant difference between proband's transmission and the gender of the parents and offspring. CONCLUSIONS: With this study, we showed that gender is truly a risk factor for migraine and that a gender-biased transmission is also observed. This reinforce the importance of identifying genes associated with migraine that are modulated by genes located in the sex chromosomes and the study of mitochondrial DNA or X-chromosome and hormonal-related effects associated with migraine susceptibility
- BDNF and CGRP interaction: implications in migraine susceptibilityPublication . Lemos, C.; Mendonça, D.; Pereira-Monteiro, J.; Barros, J.; Sequeiros, J.; Alonso, I.; Sousa, A.Abstract OBJECTIVES: Migraine pathophysiology involves several pathways. Our aims were to explore a possible role of the brain-derived neurotrophic factor gene (BDNF) in migraine susceptibility; to study, for the first time, the calcitonin gene-related peptide gene (CGRP); and a possible interaction between the two. METHODS: Using a case-control approach, four tagging single nucleotide polymorphisms (SNPs) (rs7124442, rs6265, rs11030107, and rs2049046) of BDNF and one tagging SNP-rs1553005-of CGRP were analyzed in 188 cases and 287 controls. A multivariable logistic regression was performed, adjusting for gender. Allelic and haplotypic frequencies were estimated. Interaction was assessed by a stepwise multivariable-logistic regression and confirmed by a multifactor dimensionality reduction analysis. RESULTS: No significant main effects were found; however, a significant interaction was found between BDNF and CGRP, showing an increased risk for the AT-genotype of rs2049046 and the GC-genotype of rs1553005 (odds ratio=1.88, 95% confidence interval: 1.20-2.93) for migraineurs. CONCLUSION: Our data support the hypothesis of an interaction between BDNF and CGRP in migraine susceptibility that should be further explored.
- Evidence of syntaxin 1A involvement in migraine susceptibility: a Portuguese study.Publication . Lemos, C.; Pereira-Monteiro, J.; Mendonça, D.; Ramos, E.; Barros, J.; Sequeiros, J.; Alonso, I.; Sousa, A.Abstract OBJECTIVE: To confirm syntaxin 1A as a risk factor for migraine, given that syntaxin 1A interacts with several factors in migraine pathophysiology. DESIGN: Case-control approach. SETTING: An outpatient clinic. PARTICIPANTS: In a sample of 188 migraineurs (111 without aura and 77 with aura) and 287 migraine-free controls, 3 tagging SNPs of STX1A (rs3793243, rs941298, and rs6951030) were analyzed. A backward stepwise multiple logistic regression was performed. Allelic and haplotypic frequencies were compared between cases and controls. RESULTS: We found that rs941298 and rs6951030 were risk factors for migraines. In particular, the TT genotype of rs941298 is associated with an increased risk of both migraine in general and migraine without aura; the GG and GT genotypes for rs6951030 are also associated with migraine, while the GT genotype of rs6951030 was found to be significant in the migraine without aura group. The single-nucleotide polymorphism rs3793243 did not show any significant association. In the haplotype-based analysis, we found an underrepresentation of the T-C-T haplotype (rs3793243-rs941298-rs6951030) in the global sample and in migraine without aura group. We found an enrichment of the G allele of rs6951030 for female migraineurs only. CONCLUSIONS: We confirmed the involvement of syntaxin 1A in migraine susceptibility regarding rs941298. In addition, we found rs6951030 to also be associated in Portuguese migraine patients. Sex differences should be further explored to disentangle a possible sex susceptibility in syntaxin 1A
- Interaction between γ-Aminobutyric Acid A Receptor Genes: New Evidence in Migraine SusceptibilityPublication . Quintas, M.; Neto, J.; Pereira-Monteiro, J.; Barros, J.; Sequeiros, J.; Sousa, A:; Alonso, I.; Lemos, C.Migraine is a common neurological episodic disorder with a female-to-male prevalence 3- to 4-fold higher, suggesting a possible X-linked genetic component. Our aims were to assess the role of common variants of gammaaminobutyric acid A receptor (GABAAR) genes, located in the X-chromosome, in migraine susceptibility and the possible interaction between them. An association study with 188 unrelated cases and 286 migraine-free controls age- and ethnic matched was performed. Twenty-three tagging SNPs were selected in three genes (GABRE, GABRA3 and GABRQ). Allelic, genotypic and haplotypic frequencies were compared between cases and controls. We also focused on gene-gene interactions. The AT genotype of rs3810651 of GABRQ gene was associated with an increased risk for migraine (OR: 4.07; 95% CI: 1.71-9.73, p=0.002), while the CT genotype of rs3902802 (OR: 0.41; 95% CI: 0.21-0.78, p=0.006) and GA genotype of rs2131190 of GABRA3 gene (OR: 0.53; 95% CI: 0.32-0.88, p=0.013) seem to be protective factors. All associations were found in the female group and maintained significance after Bonferroni correction. We also found three nominal associations in the allelic analyses although there were no significant results in the haplotypic analyses. Strikingly, we found strong interactions between six SNPs encoding for different subunits of GABAAR, all significant after permutation correction. To our knowledge, we show for the first time, the putative involvement of polymorphisms in GABAAR genes in migraine susceptibility and more importantly we unraveled a role for novel gene-gene interactions opening new perspectives for the development of more effective treatments.
- Monozygotic twin sisters discordant for familial hemiplegic migrainePublication . Barros, J.; Barreto, R.; Brandão, A.; Domingos, J.; Damásio, J.; Ramos, C.; Lemos, C.; Sequeiros, J.; Alonso, I.; Pereira-Monteiro, J.Background: The high concordance rate of migraine in monozygotic twin pairs has long been recognised. In the current study, we present a monozygotic twin pair discordant for familial hemiplegic migraine (FHM). Case presentations: We evaluated 12 adult family members in 2012. The twin pair was separately examined by neurologists at different time points. Mutation screening was performed for known FHM-related genes. The monozygosity of the twins was verified. Eleven individuals had a history of migraine or paroxysmal neurological symptoms, including four patients with motor aura. No mutations were detected in the CACNA1A, ATP1A2, SCN1A, PRRT2 or NOTCH3 genes. The monozygotic twin sisters, aged 52, were discordant for age of onset, motor aura and neuropsychological aura (forced thinking). Overall, the family members presented a wide range of phenotypical features. Conclusions: Familial hemiplegic migraine is a monogenic disorder that is distinct from migraine with typical aura. However, in certain families with motor aura, such as this one, it is possible that the most severe phenotype is caused by an unlikely combination of polygenic traits and non-genetic factors. In these kindreds, we propose that hemiplegic aura is only a severe and complex form of typical aura.
- Phenotypes of spinocerebellar ataxia type 6 and familial hemiplegic migraine caused by a unique CACNA1A missense mutation in patients from a large familyPublication . Alonso, I.; Barros, J.; Tuna, A.; Coelho, J.; Sequeira, J.; Silveira, I.; Coutinho, P.Background: Different mutations in the 1A-subunit of the brain P/Q-type calcium channel gene (CACNA1A) are responsible for familial hemiplegic migraine (FHM), episodic ataxia type 2, and spinocerebellar ataxia type 6 (SCA6). Missense and splice site mutations have been found in FHM and episodic ataxia type 2, respectively, whereas a CAG repeat in the CACNA1A gene was found expanded in patients with SCA6. Objective: To identify the disease causing mutation in a large family of patients with phenotypes of hemiplegic migraine with or without cerebellar signs or permanent cerebellar ataxia without migraine inherited in a dominant manner. Patients and Methods: We examined 15 patients from a large family identified through a systematic survey of hereditary ataxias being conducted in Portugal. Linkage analysis was performed with CACNA1A gene markers, and mutation analysis was performed by single strand conformational polymorphism analysis and sequencing. Results: Genetic linkage analysis with CACNA1A intragenic markers showed positive LOD scores. The maximal LOD score was obtained with the polymorphic CAG repeat (Zmax=4.47, =0). By single-strand conformational polymorphism analysis, a shift in exon 13 of the CACNA1A gene was detected in all patients.AG-to-A substitution was then identified, resulting in an arginine-to-glutamine change at codon 583 of this calcium channel 1A-subunit. Conclusions: The disease-causing mutation in this family was identified, showing that a unique mutation in the CACNA1A gene causes several phenotypes, including those of SCA6 and FHM, thus suggesting that SCA6 and FHM are not only allelic diseases but are the same disorder with a large phenotypic variability.
- A role for endothelin receptor type A in migraine without aura susceptibility? A study in Portuguese patientsPublication . Lemos, C.; Neto, J.; Pereira-Monteiro, J.; Mendonça, D.; Barros, J.; Sequeiros, J.; Alonso, I.; Sousa, A.Abstract BACKGROUND AND PURPOSE: Migraine is a common neurological disabling disorder, and anomalies of vascular function have been implied in its pathophysiology. Several findings point to a possible role of the endothelin receptor type A (EDNRA) in migraine. We aim to assess the involvement of endothelin receptor type A (EDNRA) in migraine susceptibility in a sample of Portuguese migraineurs. METHODS: Three tagging SNPs (rs702757, rs5333 and rs5335) were analysed in 188 cases - 111 without aura (MO) and 77 with aura (MA) - and 287 controls. A multivariable logistic regression was performed, including the three SNPs, adjusted for gender. Allelic and haplotypic frequencies were compared between cases and controls. Significant or promising results were confirmed by a multifactor dimensionality reduction analysis (MDR). RESULTS: We found a nominal association for the rs702757 T-allele [odds ratio (OR) = 1.44, 95% confidence intervals (CI): 1.05-1.99] and for the TT-genotype (OR = 2.34, 95% CI: 1.12-4.90) for MO, that do not remain significant after multiple test correction. A trend towards an increased risk for MA regarding the C-allele of rs5333 was also found. However, an additional MDR analysis was performed, and highly significant results were found for the two SNPs. The T-C-G haplotype (rs702757-rs5333-rs5335) was found to be significantly overrepresented in the MO subgroup, even after permutation was performed. CONCLUSIONS: Our results show additional findings for a role of EDNRA as a susceptibility factor for MO, although we cannot exclude the involvement of this gene in MA susceptibility in our population. Our study also emphasizes the need for replication of association findings in different populations.