CACNA1A R1347Q: a frequent recurrent mutation in hemiplegic migraine.

Of the 18 missense mutations in the CACNA1A gene, which are associated with familial hemiplegic migraine type 1 (FHM1), only mutations S218L, R583Q and T666M were identified in more than two independent families. Including the four novel families presented here, of which two represent de novo cases, the R1347Q mutation has now been identified in six families. A genotype-phenotype comparison of R1347Q mutation carriers revealed a wide clinical spectrum ranging from (trauma triggered) hemiplegic migraine with and without ataxia, loss of consciousness and epilepsy. R1347Q is the third most frequent mutation in hemiplegic migraine patients and should therefore be screened with priority for confirmation of clinical diagnosis. This study clearly demonstrates that the availability of multiple families better reflects the full clinical spectrum associated with FHM1 mutations.

Expanding the phenotypic spectrum of the CACNA1A gene T666M mutation: a description of 5 families with familial hemiplegic migraine.

BACKGROUND: Familial hemiplegic migraine (FHM) is a rare autosomal dominant subtype of migraine with aura. Missense mutations in the chromosome 19 CACNA1A calcium channel gene have been found in approximately half of the families. The T666M mutation, replacing a threonine by a methionine at residue number 666, is the most frequent mutation, reported in 14 independent FHM families; other mutations have so far been described in only 1 or 2 families each. The clinical features of T666M families have been reported, but the course is unknown. OBJECTIVE: To present a detailed description of the clinical features of new FHM families in which we identified the T666M mutation in our CACNA1A screening program. METHODS: As part of our ongoing genetic screening, mutation analysis of the CACNA1A gene was performed by single-strand conformational polymorphism analysis in 33 probands of families with FHM. RESULTS: We identified the T666M mutation in 5 unrelated FHM families. In 3 of the families, patients displayed cerebellar ataxia. In 1 family, some affected members with the mutation had attacks with confusion but without hemiparesis. In 1 family, patients had progressive cognitive dysfunction. CONCLUSIONS: The T666M mutation is the most frequent CACNA1A mutation in FHM; it was found in 5 of 33 FHM families at our laboratory, and in 19 of 39 families with a known mutation reported in the literature (including the present study). Screening for the T666M mutation should therefore be the first step when screening families with FHM. There is a remarkable clinical heterogeneity among families with the T666M mutation.

Episodic ataxia type 2. Three novel truncating mutations and one novel missense mutation in the CACNA1A gene.

We analysed the CACNA1A gene, located on chromosome 19p13, in three unrelated families and one sporadic case with episodic ataxia type 2 (EA-2). In two of the families and the sporadic patient, novel truncating mutations, which disrupt the reading frame and result in a premature stop of the CACNA1A protein, were identified in exons 14, 16 and 26. In the remaining family, a novel missense mutation (H253Y) was found. Of the twenty two EA-2 mutations identified thus far, including those of the present study, seventeen are truncating mutations and five are missense mutations, all resulting in an EA-2 clinical phenotype.

[From gene to disease; from CACNA1A to migraine]. / Van gen naar ziekte; van CACNA1A naar migraine.

Familial hemiplegic migraine (FHM) is a rare autosomal dominant subtype of migraine with aura. FHM is associated in half the families with mutations in the CACNA1A gene on chromosome 19P13, encoding the alpha-1A subunit of brain-specific P/Q-type calcium channels. P/Q-type calcium channels are important in neurotransmitter release. The first functional studies indicate that mutations causing FHM result in a gain or loss of function of P/Q-type calcium channels. Affected sib-pair analysis in families with migraine with and without aura indicates involvement of the CACNA1A gene in these more frequent types of migraine.

[From gene to disease; familial hemiplegic migraine as a result of mutations in a sodium-potassium pump gene]. / Van gen naar ziekte; familiaire hemiplegische migraine ten gevolge van stoornissen in een natrium-kaliumpompgen.

Familial hemiplegic migraine (FHM) is a rare, autosomal dominant subtype of migraine, associated in half of the families with mutations in the CACNA1A gene located on chromosome 19p13, which encodes the Cav2.1-subunit of brain-specific P/Q-type calcium channels. Recently, mutations in a second gene, ATP1A2 on chromosome 1q23, which encodes a sodium-potassium exchange pump subunit, have been identified. The first functional studies indicate that A TP1A2 FHM mutations result in a loss of function of the pump, leading to an increase in extracellular potassium. This is known to evoke cortical spreading depression, the underlying mechanism of migraine aura.

Severe episodic neurological deficits and permanent mental retardation in a child with a novel FHM2 ATP1A2 mutation.

OBJECTIVE: Attacks of familial hemiplegic migraine (FHM) are usually associated with transient, completely reversible symptoms. Here, we studied the ATP1A2 FHM2 gene in a young girl with episodes of both very severe and transient neurological symptoms that were triggered by mild head trauma as well as permanent mental retardation. Her family members suffered from hemiplegic and confusional migraine attacks. METHODS: Mutation analysis of the ATP1A2 gene was performed by direct sequencing of all exons and flanking intronic regions, using genomic DNA of the proband. Functional consequences of the mutation were analyzed by cellular survival assays. RESULTS: We identified a novel G615R ATP1A2 mutation in the proband and several of her family members. Functional analysis of mutant Na,K-ATPase in cellular survival assays showed a complete loss-of-function effect. INTERPRETATION: Permanent mental retardation in children may be caused by ATP1A2 mutations.

Migraine genetics: an update.

A growing interest in genetic research in migraine has resulted in the identification of several chromosomal regions that are involved in migraine. However, the identification of mutations in the genes for familial hemiplegic migraine (FHM) forms the only true molecular genetic knowledge of migraine thus far. The increased number of mutations in the FHM1 (CACNA1A) and the FHM2 (ATP1A2) genes allow studying the relationship between genetic findings in both genes and the clinical features in patients. A wide spectrum of symptoms is seen in patients. Additional cerebellar ataxia and (childhood) epilepsy can occur in FHM1 and FHM2. Functional studies show a dysfunction in ion transport as the key factor in the pathophysiology of (familial hemiplegic) migraine that predict an increased susceptibility to cortical spreading depression--the underlying mechanism of migraine aura.

The 3p21.1-p21.3 hereditary vascular retinopathy locus increases the risk for Raynaud's phenomenon and migraine.

Previously, we described a large Dutch family with hereditary vascular retinopathy (HVR), Raynaud's phenomenon and migraine. A locus for HVR was mapped on chromosome 3p21.1-p21.3, but the gene has not yet been identified. The fact that all three disorders share a vascular aetiology prompted us to study whether the HVR haplotype also contributed to Raynaud's phenomenon and migraine in this family. Whereas the parent-child transmission disequilibrium test (TDT) did not reach significance, the sibling TDT revealed that the HVR haplotype harbours a susceptibility factor for Raynaud's phenomenon and migraine. Identification of the HVR gene will improve the understanding of the pathophysiology of HVR, Raynaud's phenomenon and migraine.

Familial cyclic vomiting syndrome.

A family is described in which four members suffer from cycling vomiting syndrome (CVS), without additional symptoms. So far, only a few CVS families have been described in literature, and most patients belonging to these families had other symptoms in addition to CVS. We conclude that 'pure' CVS may also be a hereditary disorder. Its relation to migraine will be discussed.

Genetics of primary headaches.

Migraine has become an important topic in the field of complex genetic disorders. The identification of a gene on chromosome 19p encoding for an alpha 1A calcium channel subunit causing familial hemiplegic migraine has led to the classification of migraine as a channelopathy. More recently, efforts have been made to clarify the genetics of other primary headaches.

Single-fiber EMG in familial hemiplegic migraine.

Twelve familial hemiplegic migraine (FHM) patients (6 with the I1811L mutation in CACNA1A, 3 with M731T mutation in ATP1A2, and 3 without known mutations) and 10 control subjects underwent single-fiber EMG. Mean jitter did not differ significantly between patients and control subjects or among patients. No blocking was found. The results suggest that neuromuscular function is normal in FHM.

No involvement of the calcium channel gene (CACNA1A) in a family with cluster headache.

It is very likely that genetic factors play a role in the pathophysiology of cluster headache (CH). As CH shares its paroxysmal character with migraine, and migraine has been described in coexistence with CH in some families, we hypothesized that both diseases might share a genetic aetiology. In this study, we tested whether the migraine CACNA1A gene on chromosome 19 is involved in CH in an extended pedigree. Haplotype analysis did not reveal an obvious disease haplotype, and SSCP analysis of all 47 exons of the CACNA1A gene did not reveal a causative mutation. CH in this family is not caused by mutations in the CACNA1A gene.

Delayed cerebral edema and fatal coma after minor head trauma: role of the CACNA1A calcium channel subunit gene and relationship with familial hemiplegic migraine.

Trivial head trauma may be complicated by severe, sometimes even fatal, cerebral edema and coma occurring after a lucid interval ("delayed cerebral edema"). Attacks of familial hemiplegic migraine (FHM) can be triggered by minor head trauma and are sometimes accompanied by coma. Mutations in the CACNA1A calcium channel subunit gene on chromosome 19 are associated with a wide spectrum of mutation-specific episodic and chronic neurological disorders, including FHM with or without coma. We investigated the role of the CACNA1A gene in three subjects with delayed cerebral edema. Two subjects originated from a family with extreme FHM, and one subject was the previously asymptomatic daughter of a sporadic patient with hemiplegic migraine attacks. In all three subjects with delayed severe edema, we found a C-to-T substitution resulting in the substitution of serine for lysine at codon 218 (S218L) in the CACNA1A gene. The mutation was absent in nonaffected family members and 152 control individuals. Haplotype analysis excluded a common founder for both families. Neuropathological examination in one subject showed Purkinje cell loss with relative preservation of granule cells and sparing of the dentate and inferior olivary nuclei. We conclude that the novel S218L mutation in the CACNA1A calcium channel subunit gene is involved in FHM and delayed fatal cerebral edema and coma after minor head trauma. This finding may have important implications for the understanding and treatment of this dramatic syndrome.

Alternating hemiplegia of childhood: no mutations in the familial hemiplegic migraine CACNA1A gene.

INTRODUCTION: Alternating hemiplegia of childhood (AHC) is a rare disorder mainly characterized by attacks of hemiplegia and mental retardation. It has been often associated with migraine. The CACNA1A gene on chromosome 19 is involved in familial hemiplegic migraine and other episodic cerebral disorders, but also with progressive neuronal damage. METHODS: We performed mutation analysis in this gene in four AHC patients, using single strand conformation polymorphism analysis. RESULTS: We found nine polymorphisms, but no mutations in any of the 47 exons. CONCLUSIONS: Other cerebral ion channel genes remain candidate genes for AHC.

Alternating hemiplegia of childhood: no mutations in the second familial hemiplegic migraine gene ATP1A2.

Alternating hemiplegia of childhood (AHC) is a rare disorder mainly characterised by attacks of hemiplegia and mental retardation. AHC has often been associated with migraine. Previously, we have excluded the involvement of the familial hemiplegic migraine (FHM) CACNA1A gene in four patients with AHC. A second gene for FHM was discovered recently: the ATP1A2 gene on chromosome 1q23, coding for the alpha 2 subunit of Na+,K+-ATPase. We performed a mutation analysis of the ATP1A2 gene in six patients, using direct sequencing, but found no mutations in any of the 23 exons. Other cerebral ion channel genes remain candidate genes for AHC.