A G301R Na+/K+ -ATPase mutation causes familial hemiplegic migraine type 2 with cerebellar signs

The Dawn and Advancement of the Knowledge of the Genetics of Migraine

Background: Migraine is a prevalent episodic brain disorder known for recurrent attacks of unilateral headaches, accompanied by complaints of photophobia, phonophobia, nausea, and vomiting. Two main categories of migraine are migraine with aura (MA) and migraine without aura (MO). Main body: Early twin and population studies have shown a genetic basis for these disorders, and efforts have been invested since to discern the genes involved. Many techniques, including candidate-gene association studies, loci linkage studies, genome-wide association, and transcription studies, have been used for this goal. As a result, several genes were pinned with concurrent and conflicting data among studies. It is important to understand the evolution of techniques and their findings. Conclusions: This review provides a chronological understanding of the different techniques used from the dawn of migraine genetic investigations and the genes linked with the migraine subtypes.

Astrocytic Na+, K+ ATPases in physiology and pathophysiology

The Na+, K+ ATPases play a fundamental role in the homeostatic functions of astrocytes. After a brief historic prologue and discussion of the subunit composition and localization of the astrocytic Na+, K+ ATPases, the review focuses on the role of the astrocytic Na+, K+ pumps in extracellular K+ and glutamate homeostasis, intracellular Na+ and Ca2+ homeostasis and signaling, regulation of synaptic transmission and neurometabolic coupling between astrocytes and neurons. Loss-of-function mutations in the gene encoding the astrocytic α2 Na+, K+ ATPase cause a rare monogenic form of migraine with aura (familial hemiplegic migraine type 2). On the other hand, the α2 Na+, K+ ATPase is upregulated in spinal cord and brain samples from amyotrophic lateral sclerosis and Alzheimer disease patients, respectively. In the last part, the review focuses on i) the migraine relevant phenotypes shown by familial hemiplegic migraine type 2 knock-in mice with 50 % reduced expression of the astrocytic α2 Na+, K+ ATPase and the insights into the pathophysiology of migraine obtained from these genetic mouse models, and ii) the evidence that upregulation of the astrocytic α2 Na+, K+ ATPase in mouse models of amyotrophic lateral sclerosis and Alzheimer disease promotes neuroinflammation and contributes to progressive neurodegeneration.

The vascular Na,K-ATPase: clinical implications in stroke, migraine, and hypertension

In the vascular wall, the Na,K-ATPase plays an important role in the control of arterial tone. Through cSrc signaling, it contributes to the modulation of Ca2+ sensitivity in vascular smooth muscle cells. This review focuses on the potential implication of Na,K-ATPase-dependent intracellular signaling pathways in severe vascular disorders; ischemic stroke, familial migraine, and arterial hypertension. We propose similarity in the detrimental Na,K-ATPase-dependent signaling seen in these pathological conditions. The review includes a retrospective proteomics analysis investigating temporal changes after ischemic stroke. The analysis revealed that the expression of Na,K-ATPase α isoforms is down-regulated in the days and weeks following reperfusion, while downstream Na,K-ATPase-dependent cSrc kinase is up-regulated. These results are important since previous studies have linked the Na,K-ATPase-dependent cSrc signaling to futile recanalization and vasospasm after stroke. The review also explores a link between the Na,K-ATPase and migraine with aura, as reduced expression or pharmacological inhibition of the Na,K-ATPase leads to cSrc kinase signaling up-regulation and cerebral hypoperfusion. The review discusses the role of an endogenous cardiotonic steroid-like compound, ouabain, which binds to the Na,K-ATPase and initiates the intracellular cSrc signaling, in the pathophysiology of arterial hypertension. Currently, our understanding of the precise control mechanisms governing the Na,K-ATPase/cSrc kinase regulation in the vascular wall is limited. Understanding the role of vascular Na,K-ATPase signaling is essential for developing targeted treatments for cerebrovascular disorders and hypertension, as the Na,K-ATPase is implicated in the pathogenesis of these conditions and may contribute to their comorbidity.

Genetic Mechanisms of Migraine: Insights from Monogenic Migraine Mutations

Migraine is a disabling neurological disorder burdening patients globally. Through the increasing development of preclinical and clinical experimental migraine models, advancing appreciation of the extended clinical phenotype, and functional neuroimaging studies, we can further our understanding of the neurobiological basis of this highly disabling condition. Despite increasing understanding of the molecular and chemical architecture of migraine mechanisms, many areas require further investigation. Research over the last three decades has suggested that migraine has a strong genetic basis, based on the positive family history in most patients, and this has steered exploration into possibly implicated genes. In recent times, human genome-wide association studies and rodent genetic migraine models have facilitated our understanding, but most migraine seems polygenic, with the monogenic migraine mutations being considerably rarer, so further large-scale studies are required to elucidate fully the genetic underpinnings of migraine and the translation of these to clinical practice. The monogenic migraine mutations cause severe aura phenotypes, amongst other symptoms, and offer valuable insights into the biology of aura and the relationship between migraine and other conditions, such as vascular disease and sleep disorders. This review will provide an outlook of what is known about some monogenic migraine mutations, including familial hemiplegic migraine, familial advanced sleep-phase syndrome, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

Two pediatric patients with hemiplegic migraine presenting as acute encephalopathy: case reports and a literature review

Introduction

Hemiplegic migraine (HM) is a rare subtype of migraine. HM in children may be atypical in the initial stage of the disease, which could easily lead to misdiagnosis.

Methods

We report two cases of atypical hemiplegic migraine that onset as an acute encephalopathy. And a comprehensive search was performed using PubMed, Web of Science, and Scopus. We selected only papers that reported complete clinical information about the patients with CACNA1A or ATP1A2 gene mutation.

Results

Patient #1 showed a de novo mutation, c.674C>A (p. Pro225His), in exon 5 of the CACNA1A gene. And patient #2 showed a missense mutation (c.2143G>A, p. Gly715Arg) in exon 16 of the ATP1A2. Together with our two cases, a total of 160 patients (73 CACNA1A and 87 ATP1A2) were collected and summarized finally.

Discussion

Acute encephalopathy is the main manifestation of severe attacks of HM in children, which adds to the difficulty of diagnosis. Physicians should consider HM in the differential diagnosis of patients presenting with somnolence, coma, or convulsion without structural, epileptic, infectious, or inflammatory explanation. When similar clinical cases appear, gene detection is particularly important, which is conducive to early diagnosis and treatment. Early recognition and treatment of the disease can help improve the prognosis.

Neurological and psychiatric comorbidities of migraine: Concepts and future perspectives

BACKGROUND

This narrative review aims to discuss several common neurological and psychiatric disorders that show comorbidity with migraine. Not only can we gain pathophysiological insights by studying these disorders, comorbidities also have important implications for treating migraine patients in clinical practice.

METHODS

A literature search on PubMed and Embase was conducted with the keywords "comorbidity", "migraine disorders", "migraine with aura", "migraine without aura", "depression", "depressive disorders", "epilepsy", "stroke", "patent foramen ovale", "sleep wake disorders", "restless legs syndrome", "genetics", "therapeutics".

RESULTS

Several common neurological and psychiatric disorders show comorbidity with migraine. Major depression and migraine show bidirectional causality and have shared genetic factors. Dysregulation of both hypothalamic and thalamic pathways have been implicated as a possibly cause. The increased risk of ischaemic stroke in migraine likely involves spreading depolarizations. Epilepsy is not only bidirectionally related to migraine, but is also co-occurring in monogenic migraine syndromes. Neuronal hyperexcitability is an important overlapping mechanism between these conditions. Hypothalamic dysfunction is suggested as the underlying mechanism for comorbidity between sleep disorders and migraine and might explain altered circadian timing in migraine.

CONCLUSION

These comorbid conditions in migraine with distinct pathophysiological mechanisms have important implications for best treatment choices and may provide clues for future approaches.

Hypercontractile Cardiac Phenotype in Mice with Migraine-Associated Mutation in the Na+,K+-ATPase α2-Isoform

Two α-isoforms of the Na⁺,K⁺-ATPase (α₁ and α₂) are expressed in the cardiovascular system, and it is unclear which isoform is the preferential regulator of contractility. Mice heterozygous for the familial hemiplegic migraine type 2 (FHM2) associated mutation in the α₂-isoform (G301R; α₂^+/G301R mice) have decreased expression of cardiac α₂-isoform but elevated expression of the α₁-isoform. We aimed to investigate the contribution of the α₂-isoform function to the cardiac phenotype of α₂^+/G301R hearts. We hypothesized that α₂^+/G301R hearts exhibit greater contractility due to reduced expression of cardiac α₂-isoform. Variables for contractility and relaxation of isolated hearts were assessed in the Langendorff system without and in the presence of ouabain (1 µM). Atrial pacing was performed to investigate rate-dependent changes. The α₂^+/G301R hearts displayed greater contractility than WT hearts during sinus rhythm, which was rate-dependent. The inotropic effect of ouabain was more augmented in α₂^+/G301R hearts than in WT hearts during sinus rhythm and atrial pacing. In conclusion, cardiac contractility was greater in α₂^+/G301R hearts than in WT hearts under resting conditions. The inotropic effect of ouabain was rate-independent and enhanced in α₂^+/G301R hearts, which was associated with increased systolic work.

Astrocytic Glutamate Transporters and Migraine

Glutamate levels and lifetime in the brain extracellular space are dinamically regulated by a family of Na⁺- and K⁺-dependent glutamate transporters, which thereby control numerous brain functions and play a role in numerous neurological and psychiatric diseases. Migraine is a neurological disorder characterized by recurrent attacks of typically throbbing and unilateral headache and by a global dysfunction in multisensory processing. Familial hemiplegic migraine type 2 (FHM2) is a rare monogenic form of migraine with aura caused by loss-of-function mutations in the α2 Na/K ATPase (α2NKA). In the adult brain, this pump is expressed almost exclusively in astrocytes where it is colocalized with glutamate transporters. Knockin mouse models of FHM2 (FHM2 mice) show a reduced density of glutamate transporters in perisynaptic astrocytic processes (mirroring the reduced expression of α2NKA) and a reduced rate of glutamate clearance at cortical synapses during neuronal activity and sensory stimulation. Here we review the migraine-relevant alterations produced by the astrocytic glutamate transport dysfunction in FHM2 mice and their underlying mechanisms, in particular regarding the enhanced brain susceptibility to cortical spreading depression (the phenomenon that underlies migraine aura and can also initiate the headache mechanisms) and the enhanced algesic response to a migraine trigger.

Augmented Ouabain-Induced Vascular Response Reduces Cardiac Efficiency in Mice with Migraine-Associated Mutation in the Na+, K+-ATPase α2-Isoform

Heterozygous mice (α₂^+/G301R mice) for the migraine-associated mutation (G301R) in the Na⁺,K⁺-ATPase α₂-isoform have decreased expression of cardiovascular α₂-isoform. The α₂^+/G301R mice exhibit a pro-contractile vascular phenotype associated with decreased left ventricular ejection fraction. However, the integrated functional cardiovascular consequences of this phenotype remain to be addressed in vivo. We hypothesized that the vascular response to α₂-isoform-specific inhibition of the Na⁺,K⁺-ATPase by ouabain is augmented in α₂^+/G301R mice leading to reduced cardiac efficiency. Thus, we aimed to assess the functional contribution of the α₂-isoform to in vivo cardiovascular function of wild-type (WT) and α₂^+/G301R mice. Blood pressure, stroke volume, heart rate, total peripheral resistance, arterial dP/dt, and systolic time intervals were assessed in anesthetized WT and α₂^+/G301R mice. To address rate-dependent cardiac changes, cardiovascular variables were compared before and after intraperitoneal injection of ouabain (1.5 mg/kg) or vehicle during atrial pacing. The α₂^+/G301R mice showed an enhanced ouabain-induced increase in total peripheral resistance associated with reduced efficiency of systolic development compared to WT. When the hearts were paced, ouabain reduced stroke volume in α₂^+/G301R mice. In conclusion, the ouabain-induced vascular response was augmented in α₂^+/G301R mice with consequent suppression of cardiac function.

The role of Na+ -K+ -ATPase in the epileptic brain

Na+-K+-ATPase, a P-type ATP-powered ion transporter on cell membrane, plays a vital role in cellular excitability. Cellular hyperexcitability, accompanied by hypersynchronous firing, is an important basis for seizures/epilepsy. An increasing number of studies point to a significant contribution of Na+-K+-ATPase to epilepsy, although discordant results exist. In this review, we comprehensively summarize the structure and physiological function of Na+-K+-ATPase in the central nervous system and critically evaluate the role of Na+-K+-ATPase in the epileptic brain. Importantly, we further provide perspectives on some possible research directions and discuss its potential as a therapeutic target for the treatment of epilepsy.

Fluorescence lifetime imaging microscopy reveals sodium pump dimers in live cells

The sodium-potassium ATPase (Na/K-ATPase, NKA) establishes ion gradients that facilitate many physiological functions including action potentials and secondary transport processes. NKA comprises a catalytic subunit (alpha) that interacts closely with an essential subunit (beta) and regulatory transmembrane micropeptides called FXYD proteins. In the heart, a key modulatory partner is the FXYD protein phospholemman (PLM, FXYD1), but the stoichiometry of the alpha-beta-PLM regulatory complex is unknown. Here, we used fluorescence lifetime imaging and spectroscopy to investigate the structure, stoichiometry, and affinity of the NKA-regulatory complex. We observed a concentration-dependent binding of the subunits of NKA-PLM regulatory complex, with avid association of the alpha subunit with the essential beta subunit as well as lower affinity alpha-alpha and alpha-PLM interactions. These data provide the first evidence that, in intact live cells, the regulatory complex is composed of two alpha subunits associated with two beta subunits, decorated with two PLM regulatory subunits. Docking and molecular dynamics (MD) simulations generated a structural model of the complex that is consistent with our experimental observations. We propose that alpha-alpha subunit interactions support conformational coupling of the catalytic subunits, which may enhance NKA turnover rate. These observations provide insight into the pathophysiology of heart failure, wherein low NKA expression may be insufficient to support formation of the complete regulatory complex with the stoichiometry (alpha-beta-PLM)2.

Migraine-Associated Mutation in the Na,K-ATPase Leads to Disturbances in Cardiac Metabolism and Reduced Cardiac Function

Background

Mutations in ATP1A2 gene encoding the Na,K‐ATPase α₂ isoform are associated with familial hemiplegic migraine type 2. Migraine with aura is a known risk factor for heart disease. The Na,K‐ATPase is important for cardiac function, but its role for heart disease remains unknown. We hypothesized that ATP1A2 is a susceptibility gene for heart disease and aimed to assess the underlying disease mechanism.

Methods and Results

Mice heterozygous for the familial hemiplegic migraine type 2–associated G301R mutation in the Atp1a2 gene (α₂^+/G301R mice) and matching wild‐type controls were compared. Reduced expression of the Na,K‐ATPase α₂ isoform and increased expression of the α₁ isoform were observed in hearts from α₂^+/G301R mice (Western blot). Left ventricular dilation and reduced ejection fraction were shown in hearts from 8‐month‐old α₂^+/G301R mice (cardiac magnetic resonance imaging), and this was associated with reduced nocturnal blood pressure (radiotelemetry). Cardiac function and blood pressure of 3‐month‐old α₂^+/G301R mice were similar to wild‐type mice. Amplified Na,K‐ATPase–dependent Src kinase/Ras/Erk1/2 (p44/42 mitogen‐activated protein kinase) signaling was observed in hearts from 8‐month‐old α₂^+/G301R mice, and this was associated with mitochondrial uncoupling (respirometry), increased oxidative stress (malondialdehyde measurements), and a heart failure–associated metabolic shift (hyperpolarized magnetic resonance). Mitochondrial membrane potential (5,5´,6,6´‐tetrachloro‐1,1´,3,3´‐tetraethylbenzimidazolocarbocyanine iodide dye assay) and mitochondrial ultrastructure (transmission electron microscopy) were similar between the groups. Proteomics of heart tissue further suggested amplified Src/Ras/Erk1/2 signaling and increased oxidative stress and provided the molecular basis for systolic dysfunction in 8‐month‐old α₂^+/G301R mice.

Conclusions

Our findings suggest that ATP1A2 mutation leads to disturbed cardiac metabolism and reduced cardiac function mediated via Na,K‐ATPase–dependent reactive oxygen species signaling through the Src/Ras/Erk1/2 pathway.

Epilepsy in patients with familial hemiplegic migraine

OBJECTIVE

The coexistence of epilepsy in familial hemiplegic migraine (FHM) has not been reviewed systematically. We investigated the associations of epilepsy in patients with FHM with CACNA1A, ATP1A2, SCN1A or PRRT2 mutations along with clinical and genetic data.

MATERIALS AND METHODS

We performed a search in the PubMed bibliographic database and the Cochrane Library was screened for eligible studies, from April 1997 to December 2020. Additionally, Online Mendelian Inheritance in Man (OMIM) was searched for mutations in the CACNA1A, ATP1A2, SCN1A and PRRT2 genes. Brief reports, letters, and original articles about FHM and epilepsy were included in the review if their mutations and clinical course of diseases were identified.

RESULTS

Of the included patients with FHM whose information could be accessed, there were 28 families and 195 individuals, 78 of whom had epilepsy; 30 patients had focal epilepsy and 30 patients had generalized epilepsy. All mutations except ATP1A2, which could not be evaluated due to insufficient data, revealed first epilepsy then HM. In 60 patients for whom the epilepsy prognosis was evaluated, only 3.5% of patients were drug-resistant, and the remainder had a self-limited course or responded to anti-epileptic drug treatment.

CONCLUSION

Mutations in all three and possibly four FHM genes can cause epilepsy. Contrary to our expectations, the well-known epilepsy gene SCN1A mutations are not the leading cause; the highest number of cases associated with epilepsy belongs to the ATP1A2 mutation. Drug-resistant forms of epilepsy are rare in all FHM mutations, and this information is important for counseling patients.

The α2 Na+/K+-ATPase isoform mediates LPS-induced neuroinflammation

Na⁺/K⁺-ATPase is a transmembrane ion pump that is essential for the maintenance of ion gradients and regulation of multiple cellular functions. Na⁺/K⁺-ATPase has been associated with nuclear factor kappa B (NFκB) signalling, a signal associated with lipopolysaccharides (LPSs)-induced immune response in connection with activated Toll-like receptor 4 (TLR4) signalling. However, the contribution of Na⁺/K⁺-ATPase to regulating inflammatory responses remains elusive. We report that mice haploinsufficient for the astrocyte-enriched α₂Na⁺/K⁺-ATPase isoform (α₂^+/G301R mice) have a reduced proinflammatory response to LPS, accompanied by a reduced hypothermic reaction compared to wild type litter mates. Following intraperitoneal injection of LPS, gene expressions of Tnf-α, Il-1β, and Il-6 was reduced in the hypothalamus and hippocampus from α₂^+/G301R mice compared to α₂^+/+ littermates. The α₂^+/G301R mice experienced increased expression of the gene encoding an antioxidant enzyme, NRF2, in hippocampal astrocytes. Our findings indicate that α₂Na⁺/K⁺-ATPase haploinsufficiency negatively modulates LPS-induced immune responses, highlighting a rational pharmacological target for reducing LPS-induced inflammation.

Mouse Models of Familial Hemiplegic Migraine for Studying Migraine Pathophysiology

Migraine, an extremely disabling neurological disorder, has a strong genetic component. Since monogenic mi-graines (resulting from mutations or changes in a single gene) may help researchers discover migraine pathophysiology, transgenic mice models harboring gene mutations identified in Familial Hemiplegic Migraine (FHM) patients have been gen-erated. Studies in these FHM mutant mice models have shed light on the mechanisms of migraine and may aid in the identifi-cation of novel targets for treatment. More specifically, the studies shed light on how gene mutations, hormones, and other factors impact the pathophysiology of migraine. The models may also be of relevance to researchers outside the field of mi-graine as some of their aspects are relevant to pain in general. Additionally, because of the comorbidities associated with mi-graine, they share similarities with the mutant mouse models of epilepsy, stroke, and perhaps depression. Here, we review the experimental data obtained from these mutant mice and focus on how they can be used to investigate the pathophysiology of migraine, including synaptic plasticity, neuroinflammation, metabolite alterations, and molecular and behavioral mecha-nisms of pain.

Neurovascular changes in magnetic resonance imagining and single-photon emission computed tomography during migraine attack in patients with FHM2 mutations

The aim of this article is to provide neuroimaging data on cases with familial hemiplegic migraine (FHM). A 14-year-old male presented normal diffusion-weighted magnetic resonance imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) findings during his first hemiplegic migraine attack. However, magnetic resonance angiography (MRA) showed diffuse narrowing of the right middle cerebral artery. Cerebral blood flow–single-photon emission computed tomography showed right hypoperfusion. A follow-up study showed no abnormal findings. His mother had normal DWI, FLAIR, and MRA findings during her migraine attack. Both patients were diagnosed with FHM2 (p.R763H mutation in ATP1A2). This study highlights the importance of neurovascular examinations during the FHM2 headache phase. Further cases are required to clarify the pathophysiology of migraine.

Smooth muscle Ca2+ sensitization causes hypercontractility of middle cerebral arteries in mice bearing the familial hemiplegic migraine type 2 associated mutation

Familial hemiplegic migraine type 2 (FHM2) is associated with inherited point-mutations in the Na,K-ATPase α2 isoform, including G301R mutation. We hypothesized that this mutation affects specific aspects of vascular function, and thus compared cerebral and systemic arteries from heterozygote mice bearing the G301R mutation (Atp1a2^+/-G301R) with wild type (WT). Middle cerebral (MCA) and mesenteric small artery (MSA) function was compared in an isometric myograph. Cerebral blood flow was assessed with Laser speckle analysis. Intracellular Ca²⁺ and membrane potential were measured simultaneously. Protein expression was semi-quantified by immunohistochemistry. Protein phosphorylation was analysed by Western blot. MSA from Atp1a2^+/-G301R and WT showed similar contractile responses. The Atp1a2^+/-G301R MCA constricted stronger to U46619, endothelin and potassium compared to WT. This was associated with an increased depolarization, although the Ca²⁺ change was smaller than in WT. The enhanced constriction of Atp1a2^+/-G301R MCA was associated with increased cSrc activation, stronger sensitization to [Ca²⁺]_i and increased MYPT1 phosphorylation. These differences were abolished by cSrc inhibition. Atp1a2^+/-G301R mice had reduced resting blood flow through MCA in comparison with WT mice. FHM2-associated mutation leads to elevated contractility of MCA due to sensitization of the contractile machinery to Ca²⁺, which is mediated via Na,K-ATPase/Src-kinase/MYPT1 signalling.

Genetic mouse models of migraine

Mouse models of rare monogenic forms of migraine provide a unique experimental system to study the cellular and circuit mechanisms of the primary brain dysfunctions causing a migraine disorder. Here, we discuss the migraine-relevant phenotypes and the migraine-relevant functional alterations in the brain of five genetic mouse models of migraine, four of which carry mutations derived from patients with familial hemiplegic migraine (FHM) and the fifth carry a mutation from patients with both phenotypically normal MA and familial advanced sleep phase syndrome (FASPS). We focus on the latter mouse model, in which a ubiquitous serine-threonine kinase is mutated, and on two mouse models of pure FHM, in which a voltage-gated calcium channel controlling neurotransmitter release at most brain synapses and a Na/K ATPase that is expressed mainly in astrocytes in the adult brain are mutated, respectively. First, we describe the behavioral phenotypes of the genetic animal models and review the evidence that an increased susceptibility to experimentally induced cortical spreading depression (CSD) is a key migraine-relevant phenotype common to the five models. Second, we review the synaptic alterations in the cerebral cortex of the genetic models of migraine and discuss the mechanisms underlying their increased susceptibility to CSD. Third, we review the alterations in the trigeminovascular pain pathway and discuss possible implications for migraine pain mechanisms. Finally, we discuss the insights into migraine pathophysiology obtained from the genetic models of migraine, in particular regarding the mechanisms that make the brain of migraineurs susceptible to the ignition of “spontaneous” CSDs. Although the reviewed functional studies support the view of migraine as a disorder of the brain characterized by dysfunctional regulation of the excitatory/inhibitory balance in specific neuronal circuits, much work remains to be done in the genetic mouse models e.g. to identfy the relevant dysfunctional circuits and to establish whether and how the alterations in the function of specific circuits (in the cerebral cortex and/or other brain areas) are state-dependent and may, in certain conditions, favor CSD ignition and the migraine attack.

A Chinese family with familial hemiplegic migraine type 2 due to a novel missense mutation in ATP1A2

Background

ATP1A2 has been identified as the genetic cause of familial hemiplegic migraine type 2. Over 80 ATP1A2 mutations have been reported, but no data from Chinese family studies has been included. Here, we report the first familial hemiplegic migraine type 2 Chinese family with a novel missense mutation.

Methods

Clinical manifestations in the family were recorded. Blood samples from patients and the unaffected members were collected for whole-exome sequencing to identify the pathogenic mutation. Seven online softwares (SIFT, PolyPhen-2, PROVEAN, PANTHER, MutationTaster2, MutationAssessor and PMut) were used for predicting the pathogenic potential of the mutation. PredictProtein, Jpred 4 and PyMOL were used to analyze structural changes of the protein. The mutation function was further tested by Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay.

Results

All patients in the family had typical hemiplegic migraine attacks. Co-segregation of the mutation with the migraine phenotype in four generations, with 10 patients, was completed. The identified novel mutation, G762S in ATP1A2, exhibited the disease-causing feature by all the predictive softwares. The mutation impaired the local structure of the protein and decreased cell viability.

Conclusion

G762S in ATP1A2 is a novel pathogenic mutation identified in a Chinese family with familial hemiplegic migraine, which causes loss of function by changing the protein structure of the Na+/K+-ATPase α2 subunit.

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.

Increased susceptibility to cortical spreading depression and epileptiform activity in a mouse model for FHM2

Migraine is a highly prevalent, debilitating, episodic headache disorder affecting roughly 15% of the population. Familial hemiplegic migraine type 2 (FHM2) is a rare subtype of migraine caused by mutations in the ATP1A2 gene, encoding the α2 isoform of the Na+/K+-ATPase, predominantly expressed in astrocytes. Differential comorbidities such as epilepsy and psychiatric disorders manifest in patients. Using a mouse model harboring the G301R disease-mutation in the α2 isoform, we set to unravel whether α2+/G301R mice show an increased susceptibility for epilepsy and cortical spreading depression (CSD). We performed in vivo experiments involving cortical application of KCl in awake head-restrained male and female mice of different age groups (adult and aged). Interestingly, α2+/G301R mice indeed showed an increased susceptibility to both CSD and epileptiform activity, closely replicating symptoms in FHM2 patients harboring the G301R and other FHM2-causing mutations. Additionally, this epileptiform activity was superimposed on CSDs. The age-related alteration towards CSD indicates the influence of female sex hormones on migraine pathophysiology. Therefore, the FHM2, α2+/G301R mouse model can be utilized to broaden our understanding of generalized epilepsy and comorbidity hereof in migraine, and may be utilized toward future selection of possible treatment options for migraine.

Germline De Novo Mutations in ATP1A1 Cause Renal Hypomagnesemia, Refractory Seizures, and Intellectual Disability

Over the last decades, a growing spectrum of monogenic disorders of human magnesium homeostasis has been clinically characterized, and genetic studies in affected individuals have identified important molecular components of cellular and epithelial magnesium transport. Here, we describe three infants who are from non-consanguineous families and who presented with a disease phenotype consisting of generalized seizures in infancy, severe hypomagnesemia, and renal magnesium wasting. Seizures persisted despite magnesium supplementation and were associated with significant intellectual disability. Whole-exome sequencing and conventional Sanger sequencing identified heterozygous de novo mutations in the catalytic Na⁺, K⁺-ATPase α1 subunit (ATP1A1). Functional characterization of mutant Na⁺, K⁺-ATPase α1 subunits in heterologous expression systems revealed not only a loss of Na⁺, K⁺-ATPase function but also abnormal cation permeabilities, which led to membrane depolarization and possibly aggravated the effect of the loss of physiological pump activity. These findings underline the indispensable role of the α1 isoform of the Na⁺, K⁺-ATPase for renal-tubular magnesium handling and cellular ion homeostasis, as well as maintenance of physiologic neuronal activity.

Clinical Benefit of NMDA Receptor Antagonists in a Patient With ATP1A2 Gene Mutation

Mutations in the ATP1A2 gene cause familial hemiplegic migraine type 2, alternating hemiplegia of childhood, and cerebellar function deficits, epilepsy, and mental retardation. These symptoms are likely related to glutamatergic hyperexcitability. Our patient is a 12-year-old boy with a history of complex partial seizures, attention-deficit/hyperactivity disorder, and fine motor difficulty. During early childhood, he had episodes of a self-resolving right-sided hemiparesis and focal epilepsy. His seizures did not respond to several antiepileptic medications but stopped after he received valproate. His intermittent episodes of hemiplegia persisted. Additionally, he had pronounced bilateral fine motor impairment and significant executive deficits that gradually worsened. The whole exome sequencing revealed a de novo missense mutation in the ATP1A2 gene and a maternally inherited POLG gene mutation of unknown clinical significance. We hypothesized that glutamatergic excitotoxicity due to the ATP1A2 mutation contributed to the pathogenesis of our patient's condition. He was started on N-methyl-D-aspartate receptor antagonists (memantine and dextromethorphan), as well as coenzyme Q₁₀ One year later, he showed significant improvement in sustained attention, learning efficiency, general cognitive efficiency, and fine motor dexterity. We postulate that N-methyl-D-aspartate receptor antagonists were effective for behavioral, cognitive, and cerebellar symptoms in our patient with ATP1A2 gene mutation.

Cerebellar involvement in migraine

Background Although there is a great wealth of knowledge about the neurobiological processes underlying migraine and its accompanying symptoms, the mechanisms by which an attack starts remain elusive, and the disease remains undertreated. Although the vast majority of literature focuses on the involvement of the trigeminovascular systems and higher systems it innervates, such as thalamic and hypothalamic nuclei, several lines of evidence implicate the cerebellum in the pathophysiology of migraine. Aim In this review, we aim to summarize potential cerebellar involvement seen from different perspectives including the results from imaging studies, cerebellar connectivity to migraine-related brain structures, comorbidity with disorders implying cerebellar dysfunction, similarities in triggers precipitating both such disorders, and migraine and cerebellar expression of migraine-related genes and neuropeptides. We aim to inspire an increase in interest for future research on the subject. Conclusion It is hoped that future studies can provide an answer as to how the cerebellum may be involved and whether treatment options specifically targeting the cerebellum could provide alleviation of this disorder.

Glial overexpression of Dube3a causes seizures and synaptic impairments in Drosophila concomitant with down regulation of the Na+/K+ pump ATPα

Duplication 15q syndrome (Dup15q) is an autism-associated disorder co-incident with high rates of pediatric epilepsy. Additional copies of the E3 ubiquitin ligase UBE3A are thought to cause Dup15q phenotypes, yet models overexpressing UBE3A in neurons have not recapitulated the epilepsy phenotype. We show that Drosophila endogenously expresses Dube3a (fly UBE3A homolog) in glial cells and neurons, prompting an investigation into the consequences of glial Dube3a overexpression. Here we expand on previous work showing that the Na+/K+ pump ATPα is a direct ubiquitin ligase substrate of Dube3a. A robust seizure-like phenotype was observed in flies overexpressing Dube3a in glial cells, but not neurons. Glial-specific knockdown of ATPα also produced seizure-like behavior, and this phenotype was rescued by simultaneously overexpressing ATPα and Dube3a in glia. Our data provides the basis of a paradigm shift in Dup15q research given that clinical phenotypes have long been assumed to be due to neuronal UBE3A overexpression.

Pathophysiological mechanisms of migraine and epilepsy: Similarities and differences

Migraine and epilepsy are episodic disorders with distinct features, but they have some clinical and pathophysiological overlaps. We review here clinical overlaps between seizures and migraine attacks, activities of neuronal networks observed during seizures and migraine attacks, and molecular and cellular mechanisms of migraine identified in genetic forms, focusing on genetic variants identified in hemiplegic migraine and their functional effects. Epilepsy and migraine can be generated by dysfunctions of the same neuronal networks, but these dysfunctions can be disease-specific, even if pathogenic mutations target the same protein. Studies of rare monogenic forms have allowed the identification of some molecular/cellular dysfunctions that provide a window on pathological mechanisms: we have begun to disclose the tip of the iceberg.

The α2β2 isoform combination dominates the astrocytic Na+ /K+ -ATPase activity and is rendered nonfunctional by the α2.G301R familial hemiplegic migraine type 2-associated mutation

Synaptic activity results in transient elevations in extracellular K+ , clearance of which is critical for sustained function of the nervous system. The K+ clearance is, in part, accomplished by the neighboring astrocytes by mechanisms involving the Na+ /K+ -ATPase. The Na+ /K+ -ATPase consists of an α and a β subunit, each with several isoforms present in the central nervous system, of which the α2β2 and α2β1 isoform combinations are kinetically geared for astrocytic K+ clearance. While transcript analysis data designate α2β2 as predominantly astrocytic, the relative quantitative protein distribution and isoform pairing remain unknown. As cultured astrocytes altered their isoform expression in vitro, we isolated a pure astrocytic fraction from rat brain by a novel immunomagnetic separation approach in order to determine the expression levels of α and β isoforms by immunoblotting. In order to compare the abundance of isoforms in astrocytic samples, semi-quantification was carried out with polyhistidine-tagged Na+ /K+ -ATPase subunit isoforms expressed in Xenopus laevis oocytes as standards to obtain an efficiency factor for each antibody. Proximity ligation assay illustrated that α2 paired efficiently with both β1 and β2 and the semi-quantification of the astrocytic fraction indicated that the astrocytic Na+ /K+ -ATPase is dominated by α2, paired with β1 or β2 (in a 1:9 ratio). We demonstrate that while the familial hemiplegic migraine-associated α2.G301R mutant was not functionally expressed at the plasma membrane in a heterologous expression system, α2+/G301R mice displayed normal protein levels of α2 and glutamate transporters and that the one functional allele suffices to manage the general K+ dynamics.

Epilepsy in hemiplegic migraine: Genetic mutations and clinical implications

Objective

We performed a systematic review on the comorbidities of familial/sporadic hemiplegic migraine (F/SHM) with seizure/epilepsy in patients with CACNA1A, ATP1A2 or SCN1A mutations, to identify the genotypes associated and investigate for the presence of mutational hot spots.

Methods

We performed a search in MEDLINE and in the Human Gene Mutation and Leiden Open Variation Databases for mutations in the CACNA1A, ATP1A2 and SCN1A genes. After having examined the clinical characteristics of the patients, we selected those having HM and seizures, febrile seizures or epilepsy. For each gene, we determined both the frequency and the positions at protein levels of these mutations, as well as the penetrance of epilepsy within families.

Results

Concerning F/SHM-Epilepsy1 (F/SHME1) and F/SHME2 endophenotypes, we observed a prevalent involvement of the transmembrane domains, and a strong correlation in F/SHME1 when the positively charged amino acids were involved. The penetrance of epilepsy within the families was highest for patients carrying mutation in the CACNA1A gene (60%), and lower in those having SCN1A (33.3%) and ATP1A2 (30.9%) mutations.

Conclusion

Among the HM cases with seizure/epilepsy, we observed mutational hot spots in the transmembrane domains of CACNA1A and ATP1A2 proteins. These findings could lead to a better understanding of the pathological mechanisms underlying migraine and epilepsy, therein guaranteeing the most appropriate therapeutic approach.

Familial Hemiplegic Migraine with Severe Attacks: A New Report with ATP1A2 Mutation

Introduction. Familial hemiplegic migraine (FHM) is a rare disorder characterized by migraine attacks with motor weakness during the aura phase. Mutations in CACNA1A, ATP1A2, SCN1A, and PRRT2 genes have been described. Methods. To describe a mutation in ATP1A2 gene in a FHM case with especially severe and prolonged symptomatology. Results. 22-year-old woman was admitted due to migraine-type headache and sudden onset of right-sided weakness and aphasia; she had similar episodes in her childhood. Her mother was diagnosed with hemiplegic migraine without genetic confirmation. She presented with fever, decreased consciousness, left gaze preference, mixed aphasia, right facial palsy, right hemiplegia, and left crural paresis. Computed tomography (CT) showed no lesion and CT perfusion study evidenced oligohemia in left hemisphere. A normal brain magnetic resonance (MR) was obtained. Impaired consciousness and dysphasia began to improve three days after admission and mild dysphasia and right hemiparesis lasted for 10 days. No recurrences were reported during a follow-up of two years. We identified a variant in heterozygous state in ATP1A2 gene (p.Thr364Met), pathogenic according to different prediction algorithms (SIFT, PolyPhen2, MutationTaster, and Condel). Conclusion. Prolonged and severe attacks with diffuse hypoperfusion in a FHM seemed to be specially related to ATP1A2 mutations, and p.T364M should be considered.

A 10-Month-Old With Intermittent Hypotonia and Paralysis

A 10-month-old boy presented with a 1-day history of flaccid quadriplegia and dysconjugate gaze. His history was remarkable for stereotyped episodes of flaccid quadriplegia or hemiplegia, oculomotor abnormalities, and limb or neck posturing, beginning in the first days of life and becoming more frequent and more prolonged over time. The patient was healthy and developmentally normal between episodes. Results of extensive laboratory evaluations, including EEG and brain imaging studies, were negative. The patient's history, diagnostic evaluation, and final diagnosis are reviewed. This case illustrates the importance of a fundamental understanding of neurologic localization in pediatric care and a focused diagnostic approach to an infant with paroxysmal neurologic signs.

Migraine: New Molecular Mechanisms

Migraine is an episodic headache disorder affecting more than 10% of the general population. Migraine arises from a primary brain dysfunction that leads to activation and sensitization of the trigeminovascular system. A major incompletely understood issue in the neurobiology of migraine concerns the molecular and cellular mechanisms that underlie the primary brain dysfunction and lead to activation and sensitization of the trigeminovascular system, thus generating and maintaining migraine pain. Here the author reviews recent discoveries that have advanced our understanding of these mechanisms toward a unifying pathophysiological hypothesis, in which cortical spreading depression (CSD), the phenomenon underlying migraine aura, assumes a key role. In particular, the author discusses the main recent findings in the genetics and neurobiology of familial hemiplegic migraine and the insights they provide into the molecular and cellular mechanisms that may lead to the increased susceptibility of CSD in migraineurs.

The Revolution in Migraine Genetics: From Aching Channels Disorders to a Next-Generation Medicine

Channelopathies are a heterogeneous group of neurological disorders resulting from dysfunction of ion channels located in cell membranes and organelles. The clinical scenario is broad and symptoms such as generalized epilepsy (with or without fever), migraine (with or without aura), episodic ataxia and periodic muscle paralysis are some of the best known consequences of gain- or loss-of-function mutations in ion channels. We review the main clinical effects of ion channel mutations associated with a significant impact on migraine headache. Given the increasing and evolving use of genetic analysis in migraine research-greater emphasis is now placed on genetic markers of dysfunctional biological systems-we also show how novel information in rare monogenic forms of migraine might help to clarify the disease mechanisms in the general population of migraineurs. Next-generation sequencing (NGS) and more accurate and precise phenotyping strategies are expected to further increase understanding of migraine pathophysiology and genetics.

Recurrent coma and fever in familial hemiplegic migraine type 2. A prospective 15-year follow-up of a large family with a novel ATP1A2 mutation

Background Familial hemiplegic migraine (FHM) is a rare monogenic migraine subtype characterised by attacks associated with transient motor weakness. Clinical information is mainly based on reports of small families with only short follow-up. Here, we document a prospective 15-year follow-up of an extended family with FHM type 2. Patients and methods After diagnosing FHM in a patient with severe attacks associated with coma and fever, we identified eight more family members with FHM and one with possible FHM. All family members were prospectively followed for 15 years. In total 13 clinically affected and 21 clinically non-affected family members were genetically tested and repeatedly investigated. Results A novel p.Arg348Pro ATP1A2 mutation was found in 14 family members: 12 with clinical FHM, one with psychomotor retardation and possible FHM, and one without FHM features. In 9/12 (75%) family members with genetically confirmed FHM, attacks were severe, long-lasting, and often associated with impaired consciousness and fever. Such attacks were frequently misdiagnosed and treated as viral meningitis or stroke. Epilepsy was reported in three family members with FHM and in the one with psychomotor retardation and possible FHM. Ataxia was not observed. Conclusion FHM should be considered in patients with recurrent coma and fever.

Animal models of monogenic migraine

Migraine is a highly prevalent and disabling neurological disorder with a strong genetic component. Rare monogenic forms of migraine, or syndromes in which migraine frequently occurs, help scientists to unravel pathogenetic mechanisms of migraine and its comorbidities. Transgenic mouse models for rare monogenic mutations causing familial hemiplegic migraine (FHM), cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), and familial advanced sleep-phase syndrome (FASPS), have been created. Here, we review the current state of research using these mutant mice. We also discuss how currently available experimental approaches, including epigenetic studies, biomolecular analysis and optogenetic technologies, can be used for characterization of migraine genes to further unravel the functional and molecular pathways involved in migraine.

Glutamate-system defects behind psychiatric manifestations in a familial hemiplegic migraine type 2 disease-mutation mouse model

Migraine is a complex brain disorder, and understanding the complexity of this prevalent disease could improve quality of life for millions of people. Familial Hemiplegic Migraine type 2 (FHM2) is a subtype of migraine with aura and co-morbidities like epilepsy/seizures, cognitive impairments and psychiatric manifestations, such as obsessive-compulsive disorder (OCD). FHM2 disease-mutations locate to the ATP1A2 gene encoding the astrocyte-located α₂-isoform of the sodium-potassium pump (α₂Na⁺/K⁺-ATPase). We show that knock-in mice heterozygous for the FHM2-associated G301R-mutation (α₂^+/G301R) phenocopy several FHM2-relevant disease traits e.g., by mimicking mood depression and OCD. In vitro studies showed impaired glutamate uptake in hippocampal mixed astrocyte-neuron cultures from α₂^G301R/G301R E17 embryonic mice, and moreover, induction of cortical spreading depression (CSD) resulted in reduced recovery in α₂^+/G301R male mice. Moreover, NMDA-type glutamate receptor antagonists or progestin-only treatment reverted specific α₂^+/G301R behavioral phenotypes. Our findings demonstrate that studies of an in vivo relevant FHM2 disease knock-in mouse model provide a link between the female sex hormone cycle and the glutamate system and a link to co-morbid psychiatric manifestations of FHM2.

Migraine genes and the relation to gender

Migraine is an episodic brain disorder that is characterized by recurrent attacks of severe unilateral headache that are accompanied by various neurological symptoms. In addition, many patients have what is called an aura with visual and sensory disturbances. The majority of patients are female, suggesting that female hormones play an important role in the pathophysiology of the disorder. The molecular mechanisms, however, underlying this female preponderance are not well understood. It can be expected that the field of genetics that aims at identifying genetic factors that cause migraine by lowering the threshold for attacks will unravel some of these mechanisms. The 3 best known migraine genes encode ion transporters and were identified in families with familial hemiplegic migraine (FHM), a rare subtype of migraine with aura. FHM gene mutations cause alterations in mechanisms that control and modulate the neurotransmitter balance in the brain. Transgenic mice knock-in with human pathogenic mutations that were shown to exhibit some migraine-relevant features were very helpful in dissecting molecular mechanisms of migraine and pointed to a central role for cortical glutamate. In addition, transgenic mice that overexpress human RAMP1 exist and exhibit an increased sensitivity to calcitonin gene-related peptide. Findings from genetic and animal experiments on gender differences in migraine are discussed. Recently, a role for glutamate also came forward from a genome-wide association study in common migraine. By deciphering genetic and pathogenic migraine pathways, it can be expected that in the near future we will better understand mechanisms behind the female preponderance in migraine.

Acute encephalopathy in familial hemiplegic migraine with ATP1A2 mutation

Familial hemiplegic migraine is a rare subtype of migraine with aura which includes motor weakness. A 32-year-old woman with known familial hemiplegic migraine (point mutation in Exon 22 of the ATP1A2 gene) presented with an acute confusional state, after an initially typical migraine. On examination, she had fever (38°C), agitated, with a right hemiparesis and dysphasia. Electroencephalography showed slowing of α rhythm and continuous rhythmical δ activity in the left hemisphere. She recovered 48 h after the onset of encephalopathic episode. Electroencephalography after recovery showed resolution of the abnormal slowing of the α waveforms.

Genetic effects of ATP1A2 in familial hemiplegic migraine type II and animal models

Na⁺/K⁺-ATPase alpha 2 (Atp1a2) is an integral plasma membrane protein belonging to the P-type ATPase family that is responsible for maintaining the sodium (Na⁺) and potassium (K⁺) gradients across cellular membranes with hydrolysis of ATP. Atp1a2 contains two subunits, alpha and beta, with each having various isoforms and differential tissue distribution. In humans, mutations in ATP1A2 are associated with a rare form of hereditary migraines with aura known as familial hemiplegic migraine type II. Genetic studies in mice have revealed other neurological effects of Atp1a2 in mice including anxiety, fear, and learning and motor function disorders. This paper reviews the recent findings in the literature concerning Atp1a2.

Familial and sporadic hemiplegic migraine: diagnosis and treatment

OPINION STATEMENT

Hemiplegic migraine (HM) is a rare subtype of migraine with aura, characterized by transient hemiparesis during attacks. Diagnosis is based on the International Classification of Headache Disorders criteria (ICHD-II). Two types of HM are recognized: familial (FHM) and sporadic hemiplegic migraine (SHM). HM is genetically heterogeneous. Three genes have been identified (CACNA1A, ATP1A2, and SCN1A) but more, so far unknown genes, are involved. Clinically, attacks of the 3 subtypes cannot be distinguished. The diagnosis can be confirmed but not ruled out by genetic testing, because in some HM patients other, not yet identified, genes are involved. The presence of additional symptoms (such as chronic ataxia or epilepsy) may increase the likelihood of identifying a mutation. Additional diagnostics like imaging, CSF analysis, or an EEG are mainly performed to exclude other causes of focal neurological symptoms associated with headache. Conventional cerebral angiography is contraindicated in HM because this may provoke an attack. Because HM is a rare condition, no clinical treatment trials are available in this specific subgroup of migraine patients. Thus, the treatment of HM is based on empirical data, personal experience of the treating neurologist, and involves a trial-and-error strategy. Acetaminophen and NSAIDs often are the first choice in acute treatment. Although controversial in HM, triptans can be prescribed when headaches are not relieved sufficiently with common analgesics. An effective treatment for the severe and often prolonged aura symptoms is more warranted, but currently no such acute treatment is available. Prophylactic treatment can be considered when attack frequency exceeds 2 attacks per month, or when severe attacks pose a great burden that requires reduction of severity and frequency. In no strictly preferred order, flunarizine, sodium valproate, lamotrigine, verapamil, and acetazolamide can be tried. While less evidence is available for prophylactic treatment with topiramate, candesartan, and pizotifen, these drugs can also be considered. The use of propranolol in HM is more controversial, but evidence of adverse effects is insufficient to contraindicate beta-blockers.

Genetics of migraine: an update

An important genetic component of migraine was systematically established by epidemiological studies in the 1990s. Over the past 15 years, significant progress has been made in unraveling the genetic basis and pathophysiological mechanisms of familial hemiplegic migraine, a rare and severe autosomal-dominant subtype of migraine with aura. Three different causative genes (CACNA1A, ATP1A2 and SCN1A), all of which are involved in cerebral ion translocation, have been identified. Functional studies and mouse models have shown that mutations in these genes, by different mechanisms, cause a disturbed cerebral glutamate homeostasis and, thus, increase susceptibility to cortical spreading depression, the likely correlate of migraine aura. More recently, genome-wide association studies have, for the first time, detected robust risk variants associated with the more common, genetically complex types of migraine, which has generated new perspectives for genetic research in migraine. This review summarizes the current knowledge about migraine genetics, with a focus on both familial hemiplegic migraine and recent results of genome-wide association studies.

Variable manifestations of familial hemiplegic migraine associated with reversible cerebral edema in children

Three children with familial hemiplegic migraine presented with right-sided weakness, speech difficulty, altered mental status, and gait abnormalities. These persistent aura signs were accompanied by left-sided slowing and cerebral dysfunction, documented by electroencephalograms. Cranial magnetic resonance imaging revealed cortical edema restricted to the left cerebral hemisphere. Follow-up electroencephalogram and imaging studies produced normal results 1-4 months afterward. However, cognitive changes persisted. Genetic testing demonstrated variable results: one child manifested a CACNA1A mutation compatible with familial hemiplegic migraine type 1, whereas another demonstrated an ATP1A2 sequence alteration. No known mutations were evident in the third child, with minor head trauma thought to precipitate the familial hemiplegic migraine. These findings demonstrate the variable clinical and genetic heterogeneity of childhood familial hemiplegic migraine.

Migraine headache: a review of the molecular genetics of a common disorder

This tutorial summarises the state-of-the-art on migraine genetics and looks at the possible future direction of this field of research. The view of migraine as a genetic disorder, initially based on epidemiological observations of transmission of the condition within families, was subsequently confirmed by the identification of monogenic forms of "syndromic" migraine, such as familial hemiplegic migraine. We are currently witnessing a change in the way genetic analysis is used in migraine research: rather than studying modalities of inheritance in non-monogenic forms of migraine and in the persistent modalities of migraine headache, researchers are now tending to focus on the search for genetic markers of dysfunction in biological systems. One example of the evolution of migraine genetic research is provided by the recent efforts to shed light on the pharmacogenomic mechanisms of drug response in migraineurs. In addition, novel molecular approaches about to be introduced are expected to further increase knowledge on this topic and improve patient management.

Psychotic aura symptoms in familial hemiplegic migraine type 2 (ATP1A2)

INTRODUCTION

Neuropsychological symptoms are rare in familial hemiplegic migraine (FHM). There are no reports of psychotic symptoms in FHM type 2 (ATP1A2). We examined a family with a FHM phenotype due to a M731T mutation in ATP1A2. A 10-year follow-up allowed us to observe complex auras, including psychotic symptoms in two siblings.

CASE REPORT

Male, 48 years old, with an aura that included complex illusions with a feeling of time travelling, coincident with other aura features. The aura was regarded as mystical by the patient. Female, 38 years old, with a complex migraine aura, during which she believed she had the ability to time travel and was being followed by lobbyists who wanted to steal this ability from her.

DISCUSSION

FHM type 2 must be included in the list of differential diagnoses of acute psychosis in patients with a previous history of migraine aura.

Migraine- and dystonia-related disease-mutations of Na+/K+-ATPases: relevance of behavioral studies in mice to disease symptoms and neurological manifestations in humans

The two autosomal dominantly inherited neurological diseases: familial hemiplegic migraine type 2 (FHM2) and familial rapid-onset of dystonia-parkinsonism (Familial RDP) are caused by in vivo mutations of specific alpha subunits of the sodium-potassium pump (Na(+)/K(+)-ATPase). Intriguingly, patients with classical FHM2 and RDP symptoms additionally suffer from other manifestations, such as epilepsy/seizures and developmental disabilities. Recent studies of FHM2 and RDP mouse models provide valuable tools for dissecting the vital roles of the Na(+)/K(+)-ATPases, and we discuss their relevance to the complex patient symptoms and manifestations. Thus, it is interesting that mouse models targeting a specific α-isoform cause different, although still comparable, phenotypes consistent with classical symptoms and other manifestations observed in FHM2 and RDP patients. This review highlights that use of mouse models have broad potentials for future research concerning migraine and dystonia-related diseases, which will contribute towards understanding the, yet unknown, pathophysiologies.

Hemiplegic migraine, seizures, progressive spastic paraparesis, mood disorder, and coma in siblings with low systemic serotonin

Background: Serotonin has an important role in vascular resistance and blood pressure control, and a functional serotonin transporter polymorphism has been associated with migraine. Disturbances in serotonin metabolism have been associated with autism, depression, and myoclonus related conditions, but serotonin has far more functions in the body. Familial hemiplegic migraine is a rare autosomal dominant subtype of migraine with aura in which attacks are associated with hemiparesis.

Cases: We present two siblings with hemiplegic migraine, depression, progressive spastic paraparesis, myelopathy, and spinal cord atrophy. One of the sisters presented with prolonged coma after a migraine episode. Both sisters were found to have low cerebrospinal fluid serotonin metabolite (5-hydroxyindoleacetic acid), low platelet serotonin levels, and diminished serotonin transport capacity. Their clinical symptoms improved on 5-hydroxytryptophan replacement therapy. Mutational analysis of the CACNA1A and ATP1A2 genes was negative.

Conclusion: This is the first time that systemic serotonin deficiency has been described in familial hemiplegic migraine. We hypothesize that the deficiency of serotonin transport may be part of a complex cellular membrane trafficking dysfunction involving not only the serotonin transporter but also other transporters and ion channels.

Head tremor related to CACNA1A mutations

Introduction: Familial hemiplegic migraine (FHM) is characterized by the familial occurrence of migraine attacks with fully reversible transient hemiplegia. Mutations in three different genes have been identified; CACNA1A (FHM1), ATP1A2 (FHM2) and SCN1A (FHM3). Besides hemiplegia, several other symptoms have been described in FHM 1–3 mutation carriers, including epilepsy and cerebellar symptoms.

Case report: We describe two patients in whom hemiplegic attacks were not the presenting symptom, but in whom an otherwise unexplained head tremor led us to search for FHM mutations. Both patients carried a mutation in the CACNA1A gene.

Discussion: CACNA1A mutations can give significant symptoms other than (hemiplegic) migraine as reason for presentation.