Familial "Diplegic" Migraine - Description of a Family With a Novel CACNA1A Mutation

OBJECTIVE

To characterize phenotypes of a novel CACNA1A mutation causing familial hemiplegic migraine type 1.

BACKGROUND

Familial hemiplegic migraine is a rare monogenic form of migraine associated with attacks of fully reversible unilateral motor weakness. We now report a novel CACNA1A gene mutation associated with fully reversible bilateral motor weakness (diplegia).

METHODS

The proband underwent genotyping which identified a novel CACNA1A missense mutation (c.622 [isoform 1] G > A [p.Gly208Arg]). To characterize phenotypes associated with this novel mutation, the proband and 8 of her similarly affected family members underwent a semi-structured interview.

RESULTS

All 9 subjects who were interviewed met ICHD-3 phenotypic diagnostic criteria for FHM, including reporting attacks with reversible unilateral motor weakness. Additionally, 7 of 9 subjects reported attacks including reversible motor weakness affecting both sides of the body simultaneously.

CONCLUSIONS

We describe a novel CACNA1A mutation associated with migraine attacks including reversible diplegia.

Relief Following Chronic Stress Augments Spreading Depolarization Susceptibility in Familial Hemiplegic Migraine Mice

Cortical spreading depolarization (CSD) is the electrophysiological substrate of migraine aura, and a putative trigger of trigeminovascular activation and migraine headache. Many migraineurs report stress or relief after a stress triggers an attack. We tested whether various stress conditions might modulate CSD susceptibility and whether this is dependent on genetic factors. Male and female wild type and familial hemiplegic migraine type1 (FHM1) knock-in mice heterozygous for the S218L missense mutation were subjected to acute or chronic stress, or chronic stress followed by relief (36 h). Acute stress was induced by restraint and exposure to bright light and white noise (3 h). Chronic stress was induced for 28 days by two cycles of repeated exposure of mice to a rat (7 days), physical restraint (3 days), and forced swimming (3 days). Electrical CSD threshold and KCl-induced (300 mM) CSD frequency were determined in occipital cortex in vivo at the end of each protocol. Relief after chronic stress reduced the electrical CSD threshold and increased the frequency of KCl-induced CSDs in FHM1 mutants only. Acute or chronic stress without relief did not affect CSD susceptibility in either strain. Stress status did not affect CSD propagation speed, duration or amplitude. In summary, relief after chronic stress, but not acute or chronic stress alone, augments CSD in genetically susceptible mice. Therefore, enhanced CSD susceptibility may explain why, in certain patients, migraine attacks typically occur during a period of stress relief such as weekends or holidays.

In situ imaging reveals properties of purinergic signalling in trigeminal sensory ganglia in vitro

Chronic pain is supported by sterile inflammation that induces sensitisation of sensory neurons to ambient stimuli including extracellular ATP acting on purinergic P2X receptors. The development of in vitro methods for drug screening would be useful to investigate cell crosstalk and plasticity mechanisms occurring during neuronal sensitisation and sterile neuroinflammation. Thus, we studied, at single-cell level, membrane pore dilation based on the uptake of a fluorescent probe following sustained ATP-gated P2X receptor function in neurons and non-neuronal cells of trigeminal ganglion cultures from wild-type (WT) and R192Q CaV2.1 knock-in (KI) mice, a model of familial hemiplegic migraine type 1 characterised by neuronal sensitisation and higher release of soluble mediators. In WT cultures, pore responses were mainly evoked by ATP rather than benzoyl-ATP (BzATP) and partly inhibited by the P2X antagonist TNP-ATP. P2X7 receptors were expressed in trigeminal ganglia mainly by non-neuronal cells. In contrast, KI cultures showed higher expression of P2X7 receptors, stronger responses to BzATP, an effect largely prevented by prior administration of CaV2.1 blocker ω-agatoxin IVA, small interfering RNA (siRNA)-based silencing of P2X7 receptors or the P2X7 antagonist A-804598. No cell toxicity was detected with the protocols. Calcitonin gene-related peptide (CGRP), a well-known migraine mediator, potentiated BzATP-evoked membrane permeability in WT as well as R192Q KI cultures, demonstrating its modulatory role on trigeminal sensory ganglia. Our results show an advantageous experimental approach to dissect pharmacological properties potentially relevant to chronic pain and suggest that CGRP is a soluble mediator influencing purinergic P2X pore dilation and regulating inflammatory responses.

Cerebellar Atrophy and Changes in Cytokines Associated with the CACNA1A R583Q Mutation in a Russian Familial Hemiplegic Migraine Type 1 Family

Background: Immune mechanisms recently emerged as important contributors to migraine pathology with cytokines affecting neuronal excitation. Therefore, elucidating the profile of cytokines activated in various forms of migraine, including those with a known genetic cause, can help in diagnostic and therapeutic approaches.

Methods: Here we (i) performed exome sequencing to identify the causal gene mutation and (ii) measured, using Bio-Plex technology, 22 cytokines in serum of patients with familial migraine (two with hemiplegic migraine and two with migraine with aura) from a Russian family that ethnically belongs to the Tatar population. MRI scanning was used to assess cerebellar atrophy associated with migraine in mutation carriers.

Results: Whole-exome sequencing revealed the R583Q missense mutation in the CACNA1A gene in the two patients with hemiplegic migraine and cerebellar ataxia with atrophy, confirming a FHM1 disorder. Two further patients did not have the mutation and suffered from migraine with aura. Elevated serum levels of pro-inflammatory and pro-nociceptive IL-6 and IL-18 were found in all four patients (compared to a reference panel), whereas pro-apoptotic SCGF-β and TRAIL were higher only in the patients with the FHM1 mutation. Also, cytokines CXCL1, HGF, LIF, and MIF were found particularly high in the two mutation carriers, suggesting a possible role of vascular impairment and neuroinflammation in disease pathogenesis. Notably, some “algesic” cytokines, such as β-NGF and TNFβ, remained unchanged or even were down-regulated.

Conclusion: We present a detailed genetic, neurological, and biochemical characterization of a small Russian FHM1 family and revealed evidence for higher levels of specific cytokines in migraine patients that support migraine-associated neuroinflammation in the pathology of migraine.

An altered GABA-A receptor function in spinocerebellar ataxia type 6 and familial hemiplegic migraine type 1 associated with the CACNA1A gene mutation

Background

Mutations in the CACNA1A gene encoding the voltage-gated calcium channel α1A subunit have been identified in patients with autosomal dominantly inherited neurological disorders, including spinocerebellar ataxia type 6 (SCA6) and familial hemiplegic migraine type 1 (FHM1). In order to investigate the underlying pathogenesis common to these distinct phenotypic disorders, this study investigated the neuronal function of the GABAergic system and glucose metabolism in vivo using positron emission tomography (PET).

Methods

Combined PET studies with [¹¹C]-flumazenil and [¹⁸F]-fluorodeoxyglucose (FDG) were performed in three FHM1 patients and two SCA6 patients. [¹⁸F]-FDG-PET using a three-dimensional stereotactic surface projection analysis was employed to measure the cerebral metabolic rate of glucose (CMRGlc). In addition, the GABA-A receptor function was investigated using flumazenil, a selective GABA-A receptor ligand.

Results

All patients displayed a significant decrease in CMRGlc and low flumazenil binding in the cerebellum compared with the normal controls. The flumazenil binding in the temporal cortex was also decreased in two FHM1 patients.

Conclusions

Cerebellar glucose hypometabolism and an altered GABA-A receptor function are characteristic of FHM1 and SCA6.

General significance

An altered GABA-A receptor function has previously been reported in models of inherited murine cerebellar ataxia caused by a mutation in the CACNA1A gene. This study showed novel clinical characteristics of alteration in the GABA-A receptor in vivo, which may provide clinical evidence indicating a pathological mechanism common to neurological disorders associated with CACNA1A gene mutation.

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Functional brain imaging was studied in the CACNA1A gene associated diseases.

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PET study was performed on SCA6 and FHM1 patients caused by the CACNA1A mutations.

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All patients showed cerebellar GABA-A receptor impairment and glucose hypometabolism.

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GABA-A receptor impairment in the temporal cortex was observed in the FHM1 patients.

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GABA-A receptor alteration may be characteristic of neurological diseases caused by the CACNA1A mutations.