Gens i migranya. Anàlisi mutacional i estudis d'associació en pacients

[cat] La migranya és un trastorn neurològic comú que afecta un 15% de la població. Es caracteritza per l’aparició d’episodis de cefalees recurrents i incapacitants, molt sovint acompanyades d’altres símptomes com la sensibilitat a la llum, les nàusees o els vòmits. La seva prevalença és variable en funció de l’edat i el sexe, essent fins a tres vegades més freqüent en dones en etapa adolescent o adulta. Clínicament, la migranya es classifica en dos subtipus, migranya sense aura i migranya amb aura, aquesta última caracteritzada per l’aparició de símptomes neurològics que precedeixen i/o acompanyen la cefalea. La migranya comuna té una etiologia complexa, en què participen factors genètics, encara poc coneguts, i ambientals. Hi ha, però, una forma monogènica del trastorn, la migranya amb aura hemiplègica, de la qual ja s'han resolt molts casos, amb gens i mutacions descrites, i que per tant constitueix un bon punt de partida per abordar l'estudi de la migranya comuna. En aquest treball hem aprofundit en els aspectes genètics de les formes rara i comuna de migranya, en pacients amb i sense aura. S’han dut a terme cribratges mutacionals, basats en seqüenciació i anàlisi de CNVs, en pacients amb migranya hemiplègica o altres trastorns paroxístics relacionats, tot identificant diverses mutacions causals. D’altra banda, s’han realitzat estudis d’associació a escala genòmica i amb gens candidats amb l’objectiu de detectar variants de susceptibilitat a la migranya comuna. Entre les dianes dels nostres estudis hi ha els microRNAs, molècules reguladores de l'expressió gènica que no havien estat avaluades fins ara en pacients migranyosos. En últim terme, es presenten els resultats preliminars d’un estudi de transcriptòmica en un model animal de depressió cortical propagant.[eng] Migraine is a common neurological disorder that affects 15% of the population. It’s caractherized by reccurent and inhabilitating episodes of headache, often accompanied by other symptoms like photophobia, nauseas or vomiting. The prevalence of migraine is dependent on sex and age, being more frequent in adolescent and adult women. Clinically, migraine is classified in two subtypes, with and without aura, the first characterized by the appearance of neurological disturbances that preceede or accompany the migraine episode. Common migraine presents a complex ethiology, in which both genetic and environmental factors are involved. Moreover, there is a monogenic form of the disease, hemiplegic migraine, which genetic bases are known in part. This rare form of migraine turns into a good starting point to address the study of common forms of migraine. In this Thesis we have studied the genetic factors that underlie both common and rare migraine, in patients with and without aura. We have performed mutational screening, based on sequencing and CNV analysis, in patients with hemiplegic migraine and other related paroxystic disorders that have allowed the identification of several causal mutations. Moreover, case-control association studies have been performed, at both genome-wide level or on candidate genes, in order to detect risk variants for common migraine. Among the different candidates assessed, we have focused our attention mainly on microRNAs, important gene expression regulatory molecules that had not been previously explored in migraine patients. Finally, we present the preliminary results of a transcriptomic study in a rat model of cortical spreading depression

Screening of CACNA1A and ATP1A2 genes in hemiplegic migraine: clinical, genetic and functional studies

Hemiplegic migraine (HM) is a rare and severe subtype of autosomal dominant migraine, characterized by a complex aura including some degree of motor weakness. Mutations in four genes (CACNA1A, ATP1A2, SCN1A and PRRT2) have been detected in familial and in sporadic cases. This genetically and clinically heterogeneous disorder is often accompanied by permanent ataxia, epileptic seizures, mental retardation, and chronic progressive cerebellar atrophy. Here we report a mutation screening in the CACNA1A and ATP1A2 genes in 18 patients with HM. Furthermore, intragenic copy number variant (CNV) analysis was performed in CACNA1A using quantitative approaches. We identified four previously described missense CACNA1A mutations (p.Ser218Leu, p.Thr501Met, p.Arg583Gln, and p.Thr666Met) and two missense changes in the ATP1A2 gene, the previously described p.Ala606Thr and the novel variant p.Glu825Lys. No structural variants were found. This genetic screening allowed the identification of more than 30% of the disease alleles, all present in a heterozygous state. Functional consequences of the CACNA1A-p.Thr501Met mutation, previously described only in association with episodic ataxia, and ATP1A2-p.Glu825Lys, were investigated by means of electrophysiological studies, cell viability assays or Western blot analysis. Our data suggest that both these variants are disease-causing

Genome-wide association analysis identifies susceptibility loci for migraine without aura

Migraine without aura is the most common form of migraine, characterized by recurrent disabling headache and associated autonomic symptoms. To identify common genetic variants associated with this migraine type, we analyzed genome-wide association data of 2,326 clinic-based German and Dutch individuals with migraine without aura and 4,580 population-matched controls. We selected SNPs from 12 loci with 2 or more SNPs associated with P values of <1 × 10−5 for replication testing in 2,508 individuals with migraine without aura and 2,652 controls. SNPs at two of these loci showed convincing replication: at 1q22 (in MEF2D; replication P = 4.9 × 10−4; combined P = 7.06 × 10−11) and at 3p24 (near TGFBR2; replication P = 1.0 × 10−4; combined P = 1.17 × 10−9). In addition, SNPs at the PHACTR1 and ASTN2 loci showed suggestive evidence of replication (P = 0.01; combined P = 3.20 × 10−8 and P = 0.02; combined P = 3.86 × 10−8, respectively). We also replicated associations at two previously reported migraine loci in or near TRPM8 and LRP1. This study identifies the first susceptibility loci for migraine without aura, thereby expanding our knowledge of this debilitating neurological disorder

Mutation Spectrum in the CACNA1A Gene in 49 Patients with Episodic Ataxia

Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3'UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required.The funding for this study was provided by the Spanish Ministerio de Economía y Competitividad (SAF2009-13182-C01, SAF2009-13182-C03), AGAUR (2014SGR-0932, 2009SGR-0078) and Fundació La Marató de TV3 (grant 100731). These institutions had no further role in study design, collection, analysis, interpretation of data or in the submission of this paper for publication. CS and OC were supported by Ministerio de Economía y Competitividad (BES-2007-16450 and BES-2010-033895, respectively) and NF-C by Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER, ISCIII). MV-P was supported by a predoctoral grant from VHIR, Barcelona (Spain). CT was supported by the European Union (Marie Curie, PIEF-GA-2009-254930). EC-L is the recipient of the Beatriu de Pinós programme scholarship (BP-DGR 2010)

Genome-wide DNA methylation analysis in an antimigraine-treated preclinical model of cortical spreading depolarization

Background: Cortical spreading depolarization, the cause of migraine aura, is a short-lasting depolarization wave that moves across the brain cortex, transiently suppressing neuronal activity. Prophylactic treatments for migraine, such as topiramate or valproate, reduce the number of cortical spreading depression events in rodents. Objective: To investigate whether cortical spreading depolarization with and without chronic treatment with topiramate or valproate affect the DNA methylation of the cortex. Methods: Sprague-Dawley rats were intraperitoneally injected with saline, topiramate or valproate for four weeks when cortical spreading depolarization were induced and genome-wide DNA methylation was performed in the cortex of six rats per group. Results: The DNA methylation profile of the cortex was significantly modified after cortical spreading depolarization, with and without topiramate or valproate. Interestingly, topiramate reduced by almost 50% the number of differentially methylated regions, whereas valproate increased them by 17%, when comparing to the non-treated group after cortical spreading depolarization induction. The majority of the differentially methylated regions lay within intragenic regions, and the analyses of functional group over-representation retrieved several enriched functions, including functions related to protein processing in the cortical spreading depolarization without treatment group; functions related to metabolic processes in the cortical spreading depolarization with topiramate group; and functions related to synapse and ErbB, MAPK or retrograde endocannabinoid signaling in the cortical spreading depolarization with valproate group. Conclusions: Our results may provide insights into the underlying physiological mechanisms of migraine with aura and emphasize the role of epigenetics in migraine susceptibility

Mutation spectrum in the CACNA1A gene in 49 patients with episodic ataxia

Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3′UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required

Mutation spectrum in the CACNA1A gene in 49 patients with episodic ataxia

Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3′UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required

Mutation spectrum in the CACNA1A gene in 49 patients with episodic ataxia

Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3′UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required

Screening of CACNA1A and ATP1A2 genes in hemiplegic migraine : clinical, genetic, and functional studies

Hemiplegic migraine (HM) is a rare and severe subtype of autosomal dominant migraine, characterized by a complex aura including some degree of motor weakness. Mutations in four genes (CACNA1A, ATP1A2, SCN1A and PRRT2) have been detected in familial and in sporadic cases. This genetically and clinically heterogeneous disorder is often accompanied by permanent ataxia, epileptic seizures, mental retardation, and chronic progressive cerebellar atrophy. Here we report a mutation screening in the CACNA1A and ATP1A2 genes in 18 patients with HM. Furthermore, intragenic copy number variant (CNV) analysis was performed in CACNA1A using quantitative approaches. We identified four previously described missense CACNA1A mutations (p.Ser218Leu, p.Thr501Met, p.Arg583Gln, and p.Thr666Met) and two missense changes in the ATP1A2 gene, the previously described p.Ala606Thr and the novel variant p.Glu825Lys. No structural variants were found. This genetic screening allowed the identification of more than 30% of the disease alleles, all present in a heterozygous state. Functional consequences of the CACNA1A -p.Thr501Met mutation, previously described only in association with episodic ataxia, and ATP1A2 -p.Glu825Lys, were investigated by means of electrophysiological studies, cell viability assays or Western blot analysis. Our data suggest that both these variants are disease-causing