Biallelic loss of function variants in ATP1A2 cause hydrops fetalis, microcephaly, arthrogryposis and extensive cortical malformations.

The Na+/K+- ATPase acts as an ion pump maintaining the essential plasma membrane potential in all mammalian cell types, and is essential for many cellular functions. There are four α isoforms (α1, α2, α3 and α4) with distinct expression patterns, kinetic properties and substrate affinity. The α2-isoform is encoded by ATP1A2 and evidence supports its utmost importance in Cl- homeostasis in neurons, and in the function of respiratory neurons at birth. Monallelic pathogenic variants in ATP1A2 are associated with familial hemiplegic migraine type 2 (FHM2) and on rare occasions with alternating hemiplegia of childhood 1 (AHC1). To date, no instances of biallelic loss of function variants have been reported in humans. However, Atp1a2 homozygous loss of function knockout mice (α2-/- mice) show severe motor deficits, with lack of spontaneous movements, and are perinatally lethal due to absent respiratory activity. In this report we describe three newborns from two unrelated families, who died neonatally, presenting in utero with an unusual form of fetal hydrops, seizures and polyhydramnios. At birth they had multiple joint contractures (e.g. arthrogryposis), microcephaly, malformations of cortical development, dysmorphic features and severe respiratory insufficiency. Biallelic loss of function variants in ATP1A2, predicted to be pathogenic were found on whole exome sequencing. We propose that this is a distinctive new syndrome caused by complete absence of Na+/K+- ATPase α2-isoform expression.

Synaptic gain-of-function effects of mutant Cav2.1 channels in a mouse model of familial hemiplegic migraine are due to increased basal [Ca2+]i.

Specific missense mutations in the CACNA1A gene, which encodes a subunit of voltage-gated CaV2.1 channels, are associated with familial hemiplegic migraine type 1 (FHM1), a rare monogenic subtype of common migraine with aura. We used transgenic knock-in (KI) mice harboring the human pathogenic FHM1 mutation S218L to study presynaptic Ca(2+) currents, EPSCs, and in vivo activity at the calyx of Held synapse. Whole-cell patch-clamp recordings of presynaptic terminals from S218L KI mice showed a strong shift of the calcium current I-V curve to more negative potentials, leading to an increase in basal [Ca(2+)]i, increased levels of spontaneous transmitter release, faster recovery from synaptic depression, and enhanced synaptic strength despite smaller action-potential-elicited Ca(2+) currents. The gain-of-function of transmitter release of the S218L mutant was reproduced in vivo, including evidence for an increased release probability, demonstrating its relevance for glutamatergic transmission. This synaptic phenotype may explain the misbalance between excitation and inhibition in neuronal circuits resulting in a persistent hyperexcitability state and other migraine-relevant mechanisms such as an increased susceptibility to cortical spreading depression.

Matrix metalloproteinase (MMP)-2 gene polymorphisms affect circulating MMP-2 levels in patients with migraine with aura.

Matrix metalloproteinases (MMP) are involved in the disruption of blood-brain barrier (BBB) during migraine attacks. In the present study, we hypothesized that two functional polymorphisms (C(-1306)T and C(-735)T) in MMP-2 gene and MMP-2 haplotypes are associated with migraine and modify MMP-2 and tissue inhibitor of MMP (TIMP)-2 levels in migraine. Genotypes for MMP-2 polymorphisms were determined by real time-PCR using Taqman allele discrimination assays. Haplotypes were inferred using the PHASE program. Plasma MMP-2 and TIMP-2 concentrations were measured by gelatin zymography and ELISA, respectively, in 148 healthy women without history of migraine and in 204 women with migraine (153 without aura; MWA, and 51 with aura; MA). Patients with MA had higher plasma MMP-2 concentrations and MMP-2/TIMP-2 ratios than patients with MWA and controls (P<0.05). While MMP-2 genotype and haplotype distributions for the polymorphisms were similar among the groups (P>0.05), we found that the CC genotype for C(-735)T polymorphism and the CC haplotype were associated with higher plasma MMP-2 concentrations in MA group (P<0.05). Our findings may help to understand the role of MMP-2 and its genetic variants in the pathophysiology of migraine and to identify a particular group of migraine patients with increased MMP-2 levels that would benefit from the use of MMP inhibitors.

CaV2.1 voltage activated calcium channels and synaptic transmission in familial hemiplegic migraine pathogenesis.

Studies on the genetic forms of epilepsy, chronic pain, and migraine caused by mutations in ion channels have given crucial insights into the molecular mechanisms, pathogenesis, and therapeutic approaches to complex neurological disorders. In this review we focus on the role of mutated CaV2.1 (i.e., P/Q-type) voltage-activated Ca2+ channels, and on the ultimate consequences that mutations causing familial hemiplegic migraine type-1 (FHM1) have in neurotransmitter release. Transgenic mice harboring the human pathogenic FHM1 mutation R192Q or S218L (KI) have been used as models to study neurotransmission at several central and peripheral synapses. FHM1 KI mice are a powerful tool to explore presynaptic regulation associated with expression of CaV2.1 channels. Mutated CaV2.1 channels activate at more hyperpolarizing potentials and lead to a gain-of-function in synaptic transmission. This gain-of-function might underlie alterations in the excitatory/ inhibitory balance of synaptic transmission, favoring a persistent state of hyperexcitability in cortical neurons that would increase the susceptibility for cortical spreading depression (CSD), a mechanism believed to initiate the attacks of migraine with aura.

Endothelial nitric oxide synthase haplotypes associated with aura in patients with migraine.

There is strong evidence implicating nitric oxide (NO) in the pathophysiology of migraine and aura. Therefore, genetic polymorphisms in the endothelial NO synthase (eNOS) gene have been studied as candidate markers for migraine susceptibility. We compared for the first time the distribution of eNOS haplotypes including the three clinically relevant eNOS polymorphisms (T(-786)C in the promoter, rs2070744; Glu298Asp in exon 7, rs1799983; and a 27 bp variable number of tandem repeats in intron 4) and two additional tagging single-nucleotide polymorphisms (rs3918226 and rs743506) in 178 women with migraine (134 without aura and 44 with aura) and 117 healthy controls (control group). Genotypes were determined by TaqMan allele discrimination assay, real-time polymerase chain reaction, and polymerase chain reaction followed by fragment separation by electrophoresis. The GA (rs743506) genotype was more common in the control group than in women with migraine (odds ratio = 0.47, 95% confidence interval [CI] = 0.29-0.78, p < 0.01). No significant differences were found in allele distributions for the five eNOS polymorphisms. However, the haplotypes including the variants "C C a Glu G" and the variants "C C b Glu G" were more common in women with migraine with aura than in women with migraine without aura (odds ratio = 30.71, 95% CI = 1.61-586.4 and odds ratio = 17.26, 95% CI = 1.94-153.4, respectively; both p < 0.0015625). These findings suggest that these two eNOS haplotypes affect the susceptibility to the presence of aura in patients with migraine.

Gain of function in FHM-1 Cav2.1 knock-in mice is related to the shape of the action potential.

Familial hemiplegic migraine type-1 FHM-1 is caused by missense mutations in the CACNA1A gene that encodes the alpha(1A) pore-forming subunit of Ca(V)2.1 Ca(2+) channels. We used knock-in (KI) transgenic mice harboring the pathogenic FHM-1 mutation R192Q to study neurotransmission at the calyx of Held synapse and cortical layer 2/3 pyramidal cells (PCs). Using whole cell patch-clamp recordings in brain stem slices, we confirmed that KI Ca(V)2.1 Ca(2+) channels activated at more hyperpolarizing potentials. However, calyceal presynaptic calcium currents (I(pCa)) evoked by presynaptic action potentials (APs) were similar in amplitude, kinetic parameters, and neurotransmitter release. Ca(V)2.1 Ca(2+) channels in cortical layer 2/3 PCs from KI mice also showed a negative shift in their activation voltage. PCs had APs with longer durations and smaller amplitudes than the calyx of Held. AP-evoked Ca(2+) currents (I(Ca)) from PCs were larger in KI compared with wild-type (WT) mice. In contrast, when I(Ca)was evoked in PCs by calyx of Held AP waveforms, we observed no amplitude differences between WT and KI mice. In the same way, Ca(2+) currents evoked at the presynaptic terminals (I(pCa))of the calyx of Held by the AP waveforms of the PCs had larger amplitudes in R192Q KI mice that in WT. These results suggest that longer time courses of pyramidal APs were a key factor for the expression of a synaptic gain of function in the KI mice. In addition, our results indicate that consequences of FHM-1 mutations might vary according to the shape of APs in charge of triggering synaptic transmission (neurons in the calyx of Held vs. excitatory/inhibitory neurons in the cortex), adding to the complexity of the pathophysiology of migraine.

Prevalence of HLA DQB1*0602 allele in patients with migraine

BACKGROUND: Studies have shown a high prevalence of migraine among narcoleptic patients. HLA-DQB1*0602 and HLA DRB1 alleles are closely associated with narcolepsy. An increase in the HLA-DRB1 allele frequency in patients with visual aura has raised greater awareness of the genetic background in migraine. PURPOSE: Since the regions DR and DQ of the HLA are in tightly linkage desiquilibrium we hypothesize that HLA-DQB1*0602 might be associated to the pathophysiology of migraine. METHOD: We analyzed the presence of HLA DQB1*0602 allele in 50 healthy subjects with no history of migraine, 53 patients with migraine without aura and 52 patients with migraine with aura. RESULTS: There was no difference in the frequency of HLA DQB1*0602 allele when control subjects and all patients were compared. We failed to note any difference in frequencies when comparing migraine patients with and without aura. CONCLUSION: Further studies with different patient populations, with other hypothalamic markers (melatonin, hypocretin) in migraine patients may shed light on to its pathophysiology.

CONTEXTO: Estudos têm demonstrado o aumento da prevalência de enxaqueca em pacientes com narcolepsia, um distúrbio de sono associado a um gene do sistema HLA, o alelo HLA-DQB1*0602. As regiões DQ e DR do HLA estão em alto desequilíbrio de ligação e já foi descrito um aumento da freqüência do alelo HLA DRB1 em pacientes com enxaqueca com aura visual, o que fortalece uma hipótese de herança genética para a enxaqueca. OBJETIVO: Nossa hipótese é que o alelo HLA-DQB1*0602 pode estar relacionado com a fisiopatologia da enxaqueca destes pacientes. MÉTODO: Nós analisamos a presença do alelo HLA-DQB1*0602 em 50 voluntários sadios sem história de enxaqueca, 53 pacientes com enxaqueca sem aura e 52 pacientes com aura. RESULTADOS: Não houve diferença entre os controles sadios e os pacientes com enxaqueca. Não houve diferença entre os pacientes com enxaqueca com e sem aura. CONCLUSÃO: Futuros estudos com diferentes populações, com outros marcadores (melatonina e hipocretina) em pacientes com enxaqueca devem ser realizados para melhor esclarecimento de fisiopatologia.

Prevalence of HLA DQB1*0602 allele in patients with migraine.

BACKGROUND: Studies have shown a high prevalence of migraine among narcoleptic patients. HLA-DQB1*0602 and HLA DRB1 alleles are closely associated with narcolepsy. An increase in the HLA-DRB1 allele frequency in patients with visual aura has raised greater awareness of the genetic background in migraine. PURPOSE: Since the regions DR and DQ of the HLA are in tightly linkage desiquilibrium we hypothesize that HLA-DQB1*0602 might be associated to the pathophysiology of migraine. METHOD: We analyzed the presence of HLA DQB1*0602 allele in 50 healthy subjects with no history of migraine, 53 patients with migraine without aura and 52 patients with migraine with aura. RESULTS: There was no difference in the frequency of HLA DQB1*0602 allele when control subjects and all patients were compared. We failed to note any difference in frequencies when comparing migraine patients with and without aura. CONCLUSION: Further studies with different patient populations, with other hypothalamic markers (melatonin, hypocretin) in migraine patients may shed light on to its pathophysiology.

Mutation analysis of CACNA1A and ATP1A2 genes in Brazilian FHM families.

Familial hemiplegic migraine (FHM) is a rare autosomal dominant form of migraine with aura. This disease has been associated with missense mutations in the CACNA1A and ATP1A2 genes. The aim of this study was to identify whether CACNA1A and ATP1A2 are or not related to Brazilian FHM. Here we screened four Brazilian FHM families (total of 26 individuals--13 affected and 13 asymptomatic or normal) for mutations in both genes. We found an amino acid change in a member of family FHM-D (Arg2206Gly). However since this alteration is not present in all affected individuals and is present in one asymptomatic individual it should be considered a polymorphism. Further studies with additional families will be necessary to reveal the importance of both CACNA1A and ATP1A2 genes on the pathogeneses of FHM in Brazil and to test the third gene (SCN1A) in these FHM families.

Mutation analysis of CACNA1A and ATP1A2 genes in Brazilian FHM families / Análise de mutações dos genes CACNA1A e ATP1A2 em famílias brasileiras afetadas por enxaqueca hemiplégica familial

Familial hemiplegic migraine (FHM) is a rare autosomal dominant form of migraine with aura. This disease has been associated with missense mutations in the CACNA1A and ATP1A2 genes. The aim of this study was to identify whether CACNA1A and ATP1A2 are or not related to Brazilian FHM. Here we screened four Brazilian FHM families (total of 26 individuals - 13 affected and 13 asymptomatic or normal) for mutations in both genes. We found an amino acid change in a member of family FHM-D (Arg2206Gly). However since this alteration is not present in all affected individuals and is present in one asymptomatic individual it should be considered a polymorphism. Further studies with additional families will be necessary to reveal the importance of both CACNA1A and ATP1A2 genes on the pathogeneses of FHM in Brazil and to test the third gene (SCN1A) in these FHM families.

A enxaqueca hemiplégica familial (EHF) é uma forma rara de enxaqueca com aura e apresenta herança autossômica dominante. Esta doença está associada com mutações do tipo missense nos genes CACNA1A e ATP1A2. O objetivo deste estudo foi identificar se os genes CACNA1A e ATP1A2 estão ou não relacionados com a enxaqueca hemiplégica familial em famílias brasileiras. Os genes citados acima foram analisados em quatro famílias brasileiras (total de 26 indivíduos - 13 afetados e 13 assintomáticos ou normais) e uma troca de aminoácido em um membro da família FHM-D (Arg2206Gly) foi observada. Porém, esta alteração não foi identificada em todos os indivíduos afetados e está presente em um indivíduo assintomático, devendo, portanto, ser considerada um polimorfismo. Estudos adicionais nas famílias já estudadas e em outras famílias brasileiras afetadas por enxaqueca hemiplégica familial serão necessários para esclarecer a importância dos genes CACNA1A e ATP1A2 na patogênese da EHF no Brasil, bem como para testar o terceiro gene (SCN1A) relacionado à EHF.

Migraña con aura: Una mirada molecular a un problema hereditario / Migraine with aura: A molecular view to a hereditary disorder

Migraine with aura (MA) is a common neurological disorder characterized by severe episodes of headache, generally unilateral, which are preceded by a focal reversible neurological deficit. The studies on MA reveal the existence of familiar aggregation compatible with a high degree of heritability and a complex multifactorial mode of transmission. The genetic factors of MA are unknown. An association to a locus in the long arm of chromosome 4 at the level of 4q22-q25 was recently reported in families with MA in Finland. Objetive: To analyze the genomic DNA of 5 Chilean families with MA to determine if there is linkage to the locus described in Finish families. Metodology: Families with MA were selected applying the diagnostic criteria of the International Headache Society (ICD-10), in which the index case or a member of the family should have MA. The genomic DNA was extracted from peripheral lymphocytes of members of each family (n = 25). Highly polymorphic genomic markers were used for the systematic analysis of the locus on 4q22-q25. Results and Discussion: The LOD score analysis of the 5 Chilean families investigated showed absence of linkage to the marker D4S1578 (maximum 0,35; p = 0.24). Due to the complexity of MA heritability it is possible that one or more loci different from the studied region are involved in the pathophysiology of MA. The study will continue with the inclusion of more family members and isolated MA cases, with the purpose of comparing Chilean and German families in an independent sample.

La migraña con aura (MA) es una patología común, caracterizada por ataques severos de cefalea generalmente unilateral, precedidos por un déficit neurológico focal reversible. Los estudios en MA revelan la existencia de agregación familiar compatible con un alto grado de herencia y un modo de transmisión multifactorial complejo. Los factores genéticos de la MA con herencia compleja son desconocidos. En familias finlandesas con MA se encontró recientemente ligamiento a un locus en el brazo largo del cromosoma 4 a nivel de 4q22-q25. Objetivo: Analizar el DNA genómico de 5 familias chilenas con MA para determinar si hay ligamiento al locus descrito en familias finlandesas. Metodología: Se seleccionaron familias con MA aplicando los criterios diagnósticos de la Sociedad Internacional de Cefalea (ICD-10), donde el caso índice o algún miembro de la familia debían tener MA. El DNA genómico se extrajo de leucocitos en sangre periférica de miembros seleccionados de cada familia (n = 25). Se usaron marcadores genómicos altamente polimórficos (microsatélites) para el análisis sistemático del locus 4q22-q25. Resultados y Discusión: El cálculo del LOD score mostró ausencia de ligamiento en las 5 familias analizadas (máximo de 0,35; p = 0,24) con el marcador D4S1578. Dado el carácter complejo de herencia en la MA es posible que existan uno o varios loci involucrados en su etiopatogenia, distintos al de la región estudiada. El estudio se continuará a través de la ampliación de las familias estudiadas y de la recolección de casos aislados de MA, con el objetivo de realizar futuros estudios de asociación para comparar los hallazgos en familias chilenas con los de familias alemanas en una muestra independiente.

Demographic, clinical and comorbidity data in a large sample of 1,147 patients with migraine in Mexico City.

The objective was to identify the sociodemographic and clinical characteristics of a large sample of patients with migraine in Mexico City. This cross-sectional study was performed in two tertiary centers in Mexico City and affiliated hospitals. We evaluated the presence of migraine through a standardised interview according to the criteria of the International Headache Society. We studied 1,147 patients. The mean age was 37.1+/-13.6 (6-77) years. Nine hundred and twenty one patients were female (80%). The age of onset of migraine was 19.4+/-10.3 (1-69) years. Six hundred and four patients had migraine with aura (53%) and 543 without aura (47%). The female/male ratio was 4:1. One hundred and forty-seven patients had cardiovascular problems (13%), 72 had neurological problems (6%), 233 had gastrointestinal problems (20%) and 323 had psychiatric problems (28%). In this study we described the clinical characteristics of a large sample of patients with migraine in Mexico City. Our sample has similar characteristics to other countries.