Molecular genetics of migraine headaches: a review

Effect of Smoking on the Development of Migraine in Women: Nationwide Cohort Study in South Korea

Background

Smoking is known to be a significant risk factor for various diseases. Migraine, a condition requiring careful lifestyle management, currently lacks specific guidelines advocating for smoking cessation as a preventive measure. Although cross-sectional studies have suggested a potential link between smoking and an increased risk of migraine, the findings have been inconsistent and conflicting. To date, there has been no longitudinal study which investigated the effect of smoking on the risk of migraine in a prospective setting.

Objective

This longitudinal study aimed to investigate the impact of smoking on the incidence of migraine in women and examine the modifying effect of menopausal status.

Methods

Using nationally representative National Health Insurance Service (NHIS) data, women aged ≥40 years who participated in national breast cancer screening in 2009 were followed-up until the end of 2019. Baseline data on smoking status (non-, ex-, and current smoker) as well as the duration and amount of cigarette smoking were collected. A Cox proportional hazards regression model was used to examine the independent effect of smoking on the risk of incident migraine after adjusting for demographics, comorbidities, and female reproductive factors. The results were stratified by menopausal status, and an interaction analysis (smoking × menopause) was performed.

Results

In total, 1,827,129 women were included in the analysis. Women with a history of smoking exhibited a higher risk of developing migraine, compared with nonsmokers. Specifically, a higher risk of migraine was observed in women with past (adjusted hazard ratio [HR] 1.044, 95% CI 1.000-1.089) and current cigarette use (adjusted HR 1.050, 95% CI, 1.023-1.079) than in nonsmokers. The effect was greater in premenopausal women (adjusted HR 1.140, 95% CI, 1.108-1.172) than in postmenopausal women (adjusted HR 1.045, 95% CI 1.018-1.073; P<.001). The risk increased with an increased amount of smoking, with a greater association in premenopausal women (P<.001).

Conclusions

Smoking increases the risk of migraine in women, with a dose-dependent relationship. Menopause modifies this effect. Our findings suggest that smoking is an important modifiable risk factor of migraine, with a higher impact in premenopausal women. The interaction between smoking and estrogen may increase the vulnerability of the migraine brain.

Relation Between Methylenetetrahydrofolate Reductase Polymorphisms (C677T and A1298C) and Migraine Susceptibility

Migraine is a neurological disorder which impairs the patient's quality of life. Several association studies investigating the association between MTHFR gene C677T and A1298C polymorphisms and susceptibility to migraine were published. But the results were conflicting, so authors performed a meta-analysis of published case control studies to find out the exact association between MTHFR polymorphism and migraine susceptibility. Four databases were searched for suitable studies up to December, 2018. Odds ratios (OR) with 95% confidence intervals (CI) was calculated adopting additive, homozygote, co-dominant, dominant, and recessive genetic models. Results of MTHFR C677T polymorphism studies meta-analysis showed significant association with migraine risk using allele contrast, homozygote, dominant and recessive genetic models (T vs. C: OR = 1.18, 95% CI = 1.00-1.26, p = 0.05; TT vs. CC: OR = 1.24, 95% CI = 1.0-1.5, p = 0.04; CT vs. CC: OR = 1.08, 95% CI = 0.97-1.07, p = 0.25; TT + CT vs. CC: OR = 1.15, 95% CI = 1.0-1.29, p = 0.04; TT vs. CT + CC: OR = 1.97, 95% CI = 1.28-3.42, p = 0.002). However, results of MTHFR A1298 polymorphism studies meta-analysis did not show any association with migraine. Subgroup analysis based on ethnicity and migraine types i.e. migraine with aura (MA) and without aura (MO) were also performed. Results of present meta-analysis indicate overall association between MTHFR C677T polymorphism with migraine in total 24 studies, in Asian population and in MA cases but did not show any association with Caucasian population and MO cases.

Refractoriness to drugs in migraine may be the result of developing anti-drug antibodies

INTRODUCTION

Migraine is a common neurological disease and is listed second among the most disabling health conditions worldwide. Refractory migraine (RM) is a term used to emphasize the unresponsiveness of migraine to various treatment options, encompassing both episodic refractory and chronic refractory migraine. In this paper we discuss various known and possible mechanisms of pharmacological refractoriness in RM, such as possible involvement of the gut microbiome, the blood-brain barrier, migraine genetics and various mechanisms of pharmacokinetic and pharmacodynamic tolerance. Development of medication-overuse headache as a secondary disorder following migraine is also considered. We argue that the available literature is insufficient to fully explain the mechanisms of refractoriness and we present our hypothesis.

HYPOTHESIS

Refractoriness to drugs in migraine may be the result of developing anti-drug antibodies. Most migraine drugs are small molecules, which cannot elicit an immune response on their own due to their size. However, such molecules can bind to peptide carriers in their vicinity, greatly increasing their immunogenicity. A small molecule possessing this binding ability is called a hapten. Haptens form hapten-carrier complexes (HCCs), which can evoke powerful immune responses. Immune reactions to HCCs are known to be predominantly 'drug allergies' or type 1 drug hypersensitivity reactions', usually resulting from IgE or non-IgE mediated mast cell degranulation. We argue that the immune reaction to HCCs can take shape in developing neutralizing anti-drug antibodies (ADA) in the form of IgG and IgA class antibodies. Since biological therapeutics, such as various monoclonal antibodies, face the issue of ADA-induced drug tolerance, HCCs, being similar in the sense that they carry peptide antigens, are of sufficient size and may be considerably immunogenic, can be responded to in a similar way by producing neutralizing ADA. Furthermore, we argue that such responses are expected to happen more frequently than is thought, due to IgG and IgA being prevalent antibodies, which utilize their neutralizing capabilities on regular basis. Finally, it is important to consider that neutralization reactions in normal immune responses are typically asymptomatic, with the only clinical expression being progressive drug tolerance. These cases may be overshadowed by the life-threatening cases of drug allergy induced anaphylaxis, possibly leading to neutralization reactions being underrecognized.

DISCUSSION

This hypothesis aims to stimulate more research regarding drug resistance, and if it receives support from empirical evidence, it may help further elucidate the mechanisms underlying refractory diseases and contribute to the development of more effective treatment of many disorders.

A Systematic Review and Meta-Analysis of Migraine and Suicidal Ideation

BACKGROUND

Previous studies have demonstrated an association between migraine and major depressive disorder. However, relatively little is known about the relationship between suicidal ideation, with or without concurrent depression, and migraine.

OBJECTIVE

We conducted a systematic literature review to synthesize the available research focused on investigating the association of migraine with suicidal ideation.

METHODS

Relevant research papers were identified through searches of major electronic databases including PubMed, Embase (Elsevier), Web of Science (Thomson Reuters), PsycINFO (EBSCO), and Google Scholar. We performed a meta-analysis to estimate the pooled unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) for the association between migraine and suicidal ideation extracted from each study.

RESULTS

A total of 148,977 participants in 6 studies were included in this analysis. Overall, findings from available studies documented elevated odds of suicidal ideation among individuals with migraines. In unadjusted models, the odds of suicidal ideation was 2.49-fold higher among individuals with migraine (OR, 2.49; 95% CI, 2.34-2.65) compared with those without migraine. In multivariate-adjusted models, the pooled adjusted OR of suicidal ideation was 1.31 (OR, 1.31; 95% CI, 1.10-1.55).

CONCLUSIONS

A meta-analysis of available studies suggests a modest positive association between migraine and suicidal ideation. Further studies allowing for a more comprehensive investigation of the association between migraine and the full range of suicidal behaviors are warranted. A larger and more robust evidence-base may be useful to inform the clinical screening and diagnoses of comorbid conditions in migraineurs.

Spinocerebellar [corrected] Ataxia Type 6: Molecular Mechanisms and Calcium Channel Genetics

Spinocerebellar ataxia (SCA) type 6 is an autosomal dominant disease affecting cerebellar degeneration. Clinically, it is characterized by pure cerebellar dysfunction, slowly progressive unsteadiness of gait and stance, slurred speech, and abnormal eye movements with late onset. Pathological findings of SCA6 include a diffuse loss of Purkinje cells, predominantly in the cerebellar vermis. Genetically, SCA6 is caused by expansion of a trinucleotide CAG repeat in the last exon of longest isoform CACNA1A gene on chromosome 19p13.1-p13.2. Normal alleles have 4-18 repeats, while alleles causing disease contain 19-33 repeats. Due to presence of a novel internal ribosomal entry site (IRES) with the mRNA, CACNA1A encodes two structurally unrelated proteins with distinct functions within an overlapping open reading frame (ORF) of the same mRNA: (1) α1A subunit of P/Q-type voltage gated calcium channel; (2) α1ACT, a newly recognized transcription factor, with polyglutamine repeat at C-terminal end. Understanding the function of α1ACT in physiological and pathological conditions may elucidate the pathogenesis of SCA6. More importantly, the IRES, as the translational control element of α1ACT, provides a potential therapeutic target for the treatment of SCA6.

Molecular factors in migraine

Migraine is a common neurological disorder that affects 11% of adults worldwide. This disease most likely has a neurovascular origin. Migraine with aura (MA) and more common form - migraine without aura (MO) - are the two main clinical subtypes of disease. The exact pathomechanism of migraine is still unknown, but it is thought that both genetic and environmental factors are involved in this pathological process. The first genetic studies of migraine were focused on the rare subtype of MA: familial hemiplegic migraine (FHM). The genes analysed in familial and sporadic migraine are: MTHFR, KCNK18, HCRTR1, SLC6A4, STX1A, GRIA1 and GRIA3. It is possible that migraine is a multifactorial disease with polygenic influence.Recent studies have shown that the pathomechanisms of migraine involves both factors responsible for immune response and oxidative stress such as: cytokines, tyrosine metabolism, homocysteine; and factors associated with pain transmission and emotions e.g.: serotonin, hypocretin-1, calcitonin gene-related peptide, glutamate. The correlations between genetic variants of the HCRTR1 gene, the polymorphism 5-HTTLPR and hypocretin-1, and serotonin were observed. It is known that serotonin inhibits the activity of hypocretin neurons and may affect the appearance of the aura during migraine attack.The understanding of the molecular mechanisms of migraine, including genotype-phenotype correlations, may contribute to finding markers important for the diagnosis and treatment of this disease.

Mitochondrial Dysfunction and Migraine

The molecular basis of migraine is still not completely understood. An impairment of mitochondrial oxidative metabolism might play a role in the pathophysiology of this disease, by influencing neuronal information processing. Biochemical assays of platelets and muscle biopsies performed in migraine sufferers have shown a decreased activity of the respiratory chain enzymes. Studies with phosphorus magnetic resonance spectroscopy (31P-MRS) have demonstrated an impairment of the brain oxidative energy metabolism both during and between migraine attacks. However, molecular genetic studies have not detected specific mitochondrial DNA (mtDNA) mutations in patients with migraine, although other studies suggest that particular genetic markers (i.e. neutral polymorphisms or secondary mtDNA mutations) might be present in some migraine sufferers. Further studies are still needed to clarify if migraine is associated with unidentified mutations on the mtDNA or on nuclear genes that code mitochondrial proteins. In this paper, we review morphological, biochemical, imaging and genetic studies which bear on the hypothesis that migraine may be related to mitochondrial dysfunction at least in some individuals.

Sex Differences in the Transmission of Migraine

Consistent evidence demonstrates that migraine is far more common in women than in men, but the explanations for this preponderance have not been systematically evaluated. We examined whether the female preponderance is attributable to genetic factors using data from a controlled family study which included 260 probands and their 1232 first-degree adult relatives. We found that although the risk of migraine was three times greater among the relatives of probands with migraine compared with controls, there was no differential risk of migraine among the relatives of male vs. female probands with migraine. Taking these data together with other family studies, we conclude that the increased risk of migraine in females is likely to result from increased exposure to non-familial endogenous or exogenous risk factors for migraine that lower the threshold for expression of migraine in women.

Association of Migraine Headaches With Suicidal Ideation Among Pregnant Women in Lima, Peru

BACKGROUND

Suicide is a leading cause of maternal death globally, and suicide prevalence rates have been shown to be increased in those with migraine. No previous study has examined the association between migraine and suicidal ideation during pregnancy.

OBJECTIVE

To examine the association between migraine and suicidal ideation among a cohort of pregnant women.

METHODS

A cross-sectional study was conducted among 3372 pregnant women attending prenatal care clinics in Lima, Peru. Suicidal ideation and depression were assessed using the Patient Health Questionnaire-9 (PHQ-9) scale during early pregnancy. Migraine classification (including migraine and probable migraine) was based on International Classification of Headache Disorders-III beta criteria. Multivariable logistic regression analyses were performed to estimate odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

Suicidal ideation was more common among those with migraine (25.6%) as compared to those with probable migraine (22.1%, P < .001) or non-migraineurs (12.3%, P < .001). After adjusting for confounders, including depression, those with migraine or probable migraine had a 78% increased odds of suicidal ideation (OR = 1.78; 95% CI: 1.46-2.17), as compared with non-migraineurs. Women with both migraine and depression had a 4.14-fold increased odds of suicidal ideation (OR = 4.14; 95% CI: 3.17-5.42) compared to those with neither condition.

CONCLUSION

Migraine is associated with increased odds of suicidal ideation in pregnant women even when controlling for depression. These findings support the consideration of screening women with comorbid migraine and depression for suicidal behavior during pregnancy.

Impact of ESR1 Gene Polymorphisms on Migraine Susceptibility: A Meta-Analysis

An increasing number of studies have explored genetic associations between the functionally important polymorphisms in estrogen receptor 1 (ESR1) gene and migraine susceptibility. The previously reported associations have nevertheless been inconsistent.The present work incorporating the published data derived from 8 publications was performed to assess the impact of these polymorphisms on incident migraine. Strength of the genetic risk was estimated by means of an odds ratio along with the 95% confidence interval (OR and 95% CI).From the results, we found individuals who harbored the 325-GG genotype, compared with those harboring the CC genotype or CG and CC combined genotypes, had almost 50% greater risk of migraine. The same genetic models showed notable associations in subgroups of Caucasians and migraine with aura (MA). For 594G>A, a moderately increased risk of migraine was seen under AG versus GG. The AA + AG versus GG model, however, showed a borderline association with migraine. Subgroup analyses according to ethnicity and subtype of migraine provided statistical evidence of significantly increased risk of migraine in Caucasians and of a marginal association with MA, respectively. Both 325C>G and 594G>A polymorphisms showed no major effects either in males or in females.Based on the statistical data, we conclude some of the ESR1 gene polymorphisms may have major contributions to the pathogenesis of migraine in Caucasian populations.

Molecular analysis of cluster headache

OBJECTIVES

Cluster headache (CH) is characterized by severe, recurrent, unilateral attacks of extreme intensity and brief duration. Variants in a myriad of genes were studied in sporadic CH patients, often with conflicting results.

METHODS

We studied gene mutations in some candidate genes, hypocretin receptor 2, Clock, and alcohol dehydrogenase 4 (ADH4), in 54 unrelated sporadic CH patients and in 200 controls in 8 kindreds/families that included more affected and nonaffected cases. Furthermore, we performed the whole-genome scanning by comparative genomic hybridization, searching for rearrangements associated with DNA gain or loss in a subset of sporadic and familial CH and control participants.

RESULTS

The analysis of candidate genes revealed that only allele and genotype frequency of the 2 ADH4 mutations resulted significantly between sporadic CH and controls; the same mutations were homozygous in CH patients from 2 families. The comparative genomic hybridization analysis revealed 2 novel rearrangements that involved the intron regions of thyrotropin-releasing hormone-degrading enzyme and neurexin 3 (NRXN3) genes, respectively. The first arrangement was present either in CH or in controls, whereas the second one was specifically found in some sporadic and familial CH cases.

CONCLUSIONS

Our data (although obtained on a small number of cases) confirm the genetic heterogeneity of CH, suggesting that mutations in the ADH4 gene and a novel rearrangement involving NRXN3 gene might be related to CH in a subset of cases.

Systematic re-evaluation of genes from candidate gene association studies in migraine using a large genome-wide association data set

Background

Before the genome-wide association (GWA) era, many hypothesis-driven candidate gene association studies were performed that tested whether DNA variants in genes that had been selected based on prior knowledge about migraine pathophysiology were associated with migraine. Most studies involved small sample sets without robust replication, thereby making the risk of false-positive findings high. Genome-wide marker data of thousands of migraine patients and controls from the International Headache Genetics Consortium provide a unique opportunity to re-evaluate key findings from candidate gene association studies (and other non-GWA genetic studies) in a much larger data set.

Methods

We selected 21 genes from published candidate gene association studies and six additional genes from other non-GWA genetic studies in migraine. Single nucleotide polymorphisms (SNPs) in these genes, as well as in the regions 500 kb up- and downstream, were inspected in IHGC GWAS data from 5175 clinic-based migraine patients with and without aura and 13,972 controls.

Results

None of the SNPs in or near the 27 genes, including the SNPs that were previously found to be associated with migraine, reached the Bonferroni-corrected significance threshold; neither when analyzing all migraine patients together, nor when analyzing the migraine with and without aura patients or males and females separately.

Conclusion

The available migraine GWAS data provide no clear evidence for involvement of the previously reported most promising candidate genes in migraine.

No evidence of association between common European mitochondrial DNA variants in Alzheimer, Parkinson, and migraine in the Spanish population

Certain mitochondrial DNA (mtDNA) variants and haplogroups have been found to be associated with neurological disorders. Several studies have suggested that mtDNA variation could have an etiologic role in these disorders by affecting the ATP production on high-energy demanding organs, such as the brain. We have analyzed 15 mtDNA SNPs (mtSNPs) in five cohorts of cases presenting Alzheimer disease (AD), Parkinson disease (PD), and migraine, and in controls, to evaluate the role mtDNA variation in disease risk. Association tests were undertaken both for mtSNPs and mitochondrial haplogroups. No significant association was detected for any mtSNP or haplogroup in AD and PD cohorts. Two mtSNPs were associated with one migraine cohort after correcting for multiple tests, namely, T4216C and G13708A and haplogroup J (FDR q-value = 0.02; Santiago's cohort). However, this association was not confirmed in a second replication migraine series. A review of the literature reveals the existence of inconsistent findings and methodological shortcomings affecting a large proportion of mtDNA association studies on AD, PD, and migraine. A detailed inspection of the literature highlights the need for performing more rigorous methodological and statistical standards in mtDNA genetic association studies aimed to avoid false positive results of association between mtDNA variants and neurological diseases.

Spatiotemporally varying visual hallucinations: II. Spectral classification and comparison with theory

In order to better understand the nature of visual hallucinations, and to test predictions of spatiotemporally oscillating hallucinations from a recent corticothalamic model of visual dynamics, clinical descriptions of hallucinations are used to establish boundaries on the spatiotemporal frequencies observed in various disorders. Detailed comparisons with hallucinations during migraine aura demonstrate that key features are consistent with corticothalamic origin and specific abnormalities, but underline the need for more detailed quantitative data to be obtained on temporally oscillating hallucinations more generally.

Endothelial Nitric Oxide Synthase and Angiotensin Converting Enzyme Gene Polymorphisms in Migraine Patients

INTRODUCTION

In this study, we investigated the association of migraine with the Variable Number of Tandem Repeats (VNTR), repeated as 27 base pair, gene polymorphism in intron 4 of the endothelial nitric oxide synthase (eNOS) and the insertion/deletion of angiotensin converting enzyme (ACE) gene polymorphisms.

METHODS

One hundred and five migraine and ninety seven healthy female control subjects were enrolled in the study. The patients were subdivided as migraine with aura and without aura, and the frequency and severity of migraine headaches were recorded. The eNOS VNTR (eNOS 4 a/b) and ACE insertion/deletion gene polymorphisms (ACE I/D) were assessed by polymerase chain reactions.

RESULT

The allele and genotype frequencies of eNOS 4 a/b gene polymorphism showed no difference between the migraine and control groups. The genotypic distribution of the ACE I/D gene polymorphism in the migraine group significantly differed from that in the control group. The DD and ID genotype increased the risk of migraine as much as 2.571 (95% CI-1.138-5.811) and 4.453 (95% CI-2.006-9.883) compared to the II genotype. The same increased risk sustained for both genotypes in the migraine with aura subgroup, but only the ID genotype remained as the risk factor in the migraine without aura subgroup (OR-3.750, 95% CI-1.493-9.420). No association of gene polymorphisms with migraine frequency and severity was observed.

CONCLUSION

Our findings support the relationship between migraine and the ACE I/D gene polymorphism. However, no association was found between migraine and the eNOS 4 a/b gene polymorphism.

Nature and nurture of human pain

Humans are very different when it comes to pain. Some get painful piercings and tattoos; others can not stand even a flu shot. Interindividual variability is one of the main characteristics of human pain on every level including the processing of nociceptive impulses at the periphery, modification of pain signal in the central nervous system, perception of pain, and response to analgesic strategies. As for many other complex behaviors, the sources of this variability come from both nurture (environment) and nature (genes). Here, I will discuss how these factors contribute to human pain separately and via interplay and how epigenetic mechanisms add to the complexity of their effects.

Assessing risk factors for migraine: differences in gender transmission

Aim

Our aim was to assess which specific factors are contributing to an increased risk of migraine in a group of 131 Portuguese families.

Methods

We studied 319 first-degree relatives, using a multilevel approach to account for the dependency among members from the same family. We included in the model relative’s gender, the proband’s gender and age-at-onset, to evaluate if any of these variables were associated with relative’s affection status. We also included in the model proband’s migraine subtype. We further assessed female and male transmissions within the proband nuclear family.

Results

Relatives’ gender was found to be a risk factor for migraine (Odds Ratio = 2.86; 95% CI = 1.75–4.67), with females at a higher risk. When splitting probands according to their migraine subtype, we found that none of the variables studied contributed to relatives of MA-probands affection-status. Our results also show a significant difference between proband’s transmission and the gender of the parents and offspring.

Conclusions

With this study, we showed that gender is truly a risk factor for migraine and that a gender-biased transmission is also observed. This reinforce the importance of identifying genes associated with migraine that are modulated by genes located in the sex chromosomes and the study of mitochondrial DNA or X-chromosome and hormonal-related effects associated with migraine susceptibility.

R583Q CACNA1A variant in SHM1 and ataxia: case report and literature update

Familial hemiplegic migraine (FHM) type 1 is a rare monogenic dominant autosomal disease due to CACNA1A gene mutations. Besides the classical phenotype, mutations on CACNA1A gene are associated with a broader spectrum of clinical features including cerebellar ataxia, making FHM1 a complex channelopathy. We report the case of a patient carrying the p.Arg583Gln mutation affected by hemiplegic migraine and late onset ataxia and we performed a literature review about the clinical features of p.Arg583Gln. Although p.Arg583Gln mutations are associated with a heterogeneous phenotype, carriers present cerebellar signs which consisted generally in ataxia and dysmetria, with intention tremor appearing mostly in advanced age, often progressive and permanent. The heterogeneous spectrum of CACNA1A gene mutations probably causes sporadic hemiplegic migraine (SHM) to be misdiagnosed. Given the therapeutic opportunities, SHM/FHM1 should be considered in differential diagnosis of patients with cerebellar ataxia and migraine with aura.

Spinocerebellar ataxia type 6

The autosomal dominant spinocerebellar ataxias (SCA) are a genetically heterogeneous group of neurodegenerative disorders characterized by progressive motor incoordination, in some cases with ataxia alone and in others in association with additional progressive neurological deficits. Spinocerebellar ataxia type 6 (SCA6) is the prototype of a pure cerebellar ataxia, associated with a severe form of progressive ataxia and cerebellar dysfunction. SCA6, originally classified as such by Zhuchenko et al. (1997), is caused by a CAG repeat expansion in the CACNA1A gene which encodes the α1A subunit of the P/Q-type voltage-gated calcium channel. SCA6 is one of ten polyglutamine-encoding CAG nucleotide repeat expansion disorders comprising other neurodegenerative disorders such as Huntington's disease. The present review describes clinical, genetic, and pathological manifestations associated with this illness. Currently, there is no treatment for this neurodegenerative disease. Successful therapeutic strategies must target a valid pathological mechanism; thus, understanding the underlying mechanisms of disease is crucial to finding a proper treatment. Hence, this chapter will discuss as well the molecular mechanisms possibly associated with SCA6 pathology and their implication for the development of future treatment.

Cross-prevalence of migraine and bipolar disorder

OBJECTIVE

In two related studies, we explored the prevalence of migraine and its associated clinical characteristics in patients with bipolar disorder (BD) as well as psychiatric morbidity in patients treated for migraine.

METHOD

The first study included 323 subjects with BD type I (BD I) or BD type II (BD II), diagnosed using the Schedule for Affective Disorders and Schizophrenia, Lifetime version (SADS-L) format, or the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID). Migraine history was assessed by means of a structured questionnaire. In a second sample of 102 migraine patients, we investigated current and lifetime psychiatric morbidity using the SADS-L. Statistical analyses were conducted using nonparametric analysis and log-linear models.

RESULTS

A total of 24.5% of BD patients had comorbid migraine; those with BD II had a higher prevalence (34.8%) compared to BD I (19.1%) (p < 0.005). BD patients with comorbid migraine had significantly higher rates of suicidal behaviour, social phobia, panic disorder, generalized anxiety disorder, and obsessive-compulsive disorder (all p < 0.05). In the sample of migraine patients, 34.3% had a current psychiatric diagnosis, and 73.5% had a lifetime psychiatric diagnosis. The prevalence of BD I was 4.9%, and 7.8% for BD II.

DISCUSSION

Migraine is prevalent within the BD population, particularly among BD II subjects. It is associated with an increased risk of suicidal behaviour and comorbid anxiety disorders. Conversely, migraine sufferers have high rates of current and lifetime psychopathology. A greater understanding of this comorbidity may contribute to our knowledge of the underlying mechanisms of BD.

High frequency of migraine-only patients negative for the 3243 A>G tRNALeu mtDNA mutation in two MELAS families

Migraine is associated with stroke-like episodes in mitochondrial encephalomyopathy, lactic acidosis, stroke-like syndrome (MELAS). Moreover, abnormalities of oxidative phosphorylation are also reported in migraine. We studied two maternal lineages with MELAS and chronic progressive external ophthalmoplegia (CPEO) affected probands carrying the 3243 A>G tRNALeu (MELAS) mutation, remarkable for a high frequency of subjects suffering only migraine. Thus, migraine could be a monosymptomatic expression of the MELAS mutation. We assessed the 3243 A>G tRNALeu mutational load in skeletal muscle and other somatic tissues from the migraine-only subjects, as well as lactic acid levels after exercise. All migraine-only subjects did not carry the MELAS mutation. Muscle biopsy showed mild mitochondrial abnormalities in the non-mutant, migraine-only subjects and, occasionally, abnormal lactic acid. Clear features of mitochondrial myopathy and pathological lactic acid characterised the subjects carrying the MELAS mutation. Our study demonstrates that migraine-only subjects lacked the MELAS mutation, but still had a possible mtDNA-associated genetic predisposition, being maternally related and having some evidence of impaired mitochondrial oxidative phosphorylation.

Association study of the serotoninergic system in migraine in the Spanish population

In order to evaluate the contribution of 19 serotonin-related genes to the susceptibility to migraine in a Spanish population we performed a case-control association study of 122 single nucleotide polymorphisms (SNPs), selected according to genetic coverage parameters, in 528 migraine patients -308 with migraine without aura (MO) and 220 with migraine with aura (MA)- and 528 sex-matched migraine-free controls. The single-marker analysis identified nominal associations with the migraine phenotype or with the MO or MA subtypes. The multiple-marker analysis revealed risk haplotypes in three genes that remained significantly associated with migraine after correction by permutations. Two-marker risk haplotypes were identified in the HTR2B (rs16827801T-rs10194776G) and MAOA (rs3027400G-rs2072743C) genes conferring susceptibility to MO, and a four-marker haplotype in DDC was specific of MA (rs2329340A-rs11974297C-rs2044859T-rs11761683G). The present study supports the involvement of HTR2B and MAOA genes in the genetic predisposition to MO, while DDC might confer susceptibility to MA. These results suggest a differential involvement of serotonin-related genes in the genetic background of MO and MA.

Lack of association of endothelial nitric oxide synthase polymorphisms and migraine

OBJECTIVE

The aim of this study was to evaluate if 2 functional endothelial nitric oxide synthase (eNOS) gene polymorphisms might be risk factors for migraine.

BACKGROUND

Nitric oxide synthase promotes the synthesis of nitric oxide (NO). NO is a potent vasodilator and mediates several processes involved in migraine pathophysiology. Only one study has suggested an association with migraine with aura.

METHODS

We performed a sex- and age-matched case-control study using 2 eNOS polymorphisms (rs1800779 and rs1799983), which are in linkage disequilibrium. Genotypes were obtained with allele-specific probes in a real-time polymerase chain reaction assay. Genotypic and allelic distributions were compared with chi(2) method. We also estimated the reconstructed haplotypes and calculated ORs for individual haplotypes.

RESULTS

A total of 337 migraine patients (188 with aura) and 341 healthy controls were recruited. We found no significant differences in the distribution of genotypes and alleles for either polymorphism among clinical subgroups. Neither rs1800779 nor rs1799983 polymorphisms increased the risk for suffering from migraine aura.

CONCLUSIONS

As others have previously reported, we failed to demonstrate genetic association of the eNOS gene with migraine.

Migraine: an overview

The pathophysiology of migraine is not completely understood and continues to be investigated. The complexity of interactions taking place in the sensory neuronal network with the mediation of all different neurotransmitters involved gives the measure of the extreme difficulty connected with the knowledge of migraine pathogenesis and in particular of its cardinal sign. Neuronal components are relevant in migraine pathophysiology: there could be a generalized interictal abnormal excitability of the cerebral cortex in migraine, possibly favoring the occurrence of spreading depression with consequent activation of the trigeminal system. Many theories have been formulated in these last sixty years about the pathogenesis of migraine and other forms of primary headache, but the problem is still far to be fully clarified. The present review is focused on the description of different theories on the migraine pathogenesis. This review is dedicated to the memory of Prof. Alfredo Bianchi.

Psychiatric disorders and headache familial recurrence: a study on 200 children and their parents

The main aim of the study was to examine the relationship between headache and familial recurrence of psychiatric disorders in parents and their children. Headache history and symptomatology have been collected in a clinical sample of 200 patients and their families, using a semi-structured interview (ICHD-II criteria). Psychiatric comorbidity was assessed by DSM-IV criteria. Chi squares and a loglinear analysis were computed in order to evaluate the main effects and interactions between the following factors: frequency and headache subtypes (migraine/not-migraine) in children, headache (migraine/not-migraine-absent/present) in parents, headache (absent/present) in grandparents, and psychiatric comorbidity (absent/present) have been analyzed: 94 mothers (47%) and 51 fathers (25.5%) had at least one psychiatric disorder, mainly mood and anxiety disorders. Considering the significant prevalence of Psi-co in children (P < 0.0001), we compared it with the presence of familiarity to headache: a significant interaction has been found (P < 0.05) showing that migraineurs with high familial recurrence of headache had a higher percentage (74.65%) of psychiatric disorders, than no-migraineurs (52.17%). Absence of headache familial loading seems to be related to psi-co only in no-migraine headache (87.5 vs. 45.5%). The occurrence of psychiatric disorders is high in children with headache, but a very different pattern seems to characterize migraine (familial co-transmission of migraine and Psi-Co?) if compared with non-migraine headache.

Multilocus analyses reveal involvement of the ESR1, ESR2, and FSHR genes in migraine

OBJECTIVE

Female hormone genes have been investigated in migraine in recent years. Research in this field has been controversial, especially in regard to ESR1 gene findings. None of the reports have yet to approach the problem from a multigenic point of view.

METHODS

We investigated 5 polymorphisms implicated in female hormone metabolism (FSHR, CYP19A1, ESR1, NRIP1, and ESR2) in a cohort of 730 subjects matched for age and sex. The effect of gene-gene interaction was assessed using the set association approach, and the corresponding haplotypes were studied with PM Plus software. To corroborate initial results, we analyzed the selected markers using a cohort of 134 families in which 168 trios were suitable for transmission-disequilibrium test (TDT) analysis under the migraine with aura (MA) phenotype.

RESULTS

A total of 356 consecutive migraine patients (198 with MA [76% females] and 158 migraine without aura [MO, 74% females], and 374 matched controls [71% females]) were genotyped. In the 2-point analyses, the ESR1 and ESR2 polymorphisms showed nominal association under MA/MO phenotype, and this association was higher with the FSHR polymorphism in MA females (P = .004, uncorrected). Using the SUMSTAT program, we observed ESR2-ESR1-FSHR significant gene-gene interaction, suggesting association with the MA/MO phenotype (P = .005; P = .003 in females), and with MA alone (P = .021; P = .030 for females).We corroborated that ESR2-ESR1-FSHR haplotypes interacted for migraine under a model-free hypothesis (empirical P = .010 for the whole sample; P = .001 for females), and the association was stronger for the MA phenotype alone (empirical P = 5.0e-4, under the heterogeneity model; P = .001 for females). These results were corroborated using family-based association approaches. We observed nominal association for ESR2 and ESR1 (P = .031 and .034, respectively) in the TDT study, and significant association for ESR1 using family-based association test statistics. Haplotype-TDT analyses showed further significant gene-gene interaction for ESR1-ESR2 (global P = .009), ESR2-FSHR (global P = .011), and nominally significant interaction for ESR2-ESR1-FSHR genes (global P = .037).

CONCLUSION

We found significant association of female hormone metabolism polymorphisms under the perspective of multigene approach.

Migraine as a sex-conditioned inherited disorder: evidences from China and the world

Migraine is a complex and heterogeneous disorder. Although several genetic models has been proposed including autosomal-dominant/autosomal recessive, sex-linked, sex-limited, mitochondrial, and multi-gene, none of these models can well-explain the transmission of the disease. We hypothesied that migraine is a sex-conditioned inherited disorder (autosomal dominant in females and autosomal recessive in males). This hypothesis is supported by the evidence such as the locations of genes associated with familial hemiplegic migraine, possibly "typical" migraine as well (dominantly on chromosome 19p, 1q, and 2q), male:female ratio of prevalence (1:2-1:4), the mostly youth-onset, the provocation by the contraceptives, the induction by menstruation, and the self-limitation after menopause. Female sex-hormones appear to be the key contributor to a higher prevalence of migraine in female. Socio-environmental factors may also play an important role.

Investigation between the S377G3 GATA-4 polymorphism and migraine

Migraine is a common and painful neurological disorder, with genetic and environmental components. Several conditions have been shown to be comorbid with migraine, notably a cardiac malformation affecting the interatrial septum and leading to patent foramen ovale (PFO). Mutations in the development regulatory gene GATA-4, located on human chromosome 8p23.1-p22, have been found to be responsible for some cases of congenital heart defects including PFO. To determine whether the GATA-4 gene is involved in migraine, the present study performed an association analysis of a common GATA-4 variant that results in a change of amino acid (S377G), in a large case/control population (275 unrelated Caucasian migraineurs versus 275 control individuals). The results showed that there was no significant association for this polymorphism between migraine and controls (chi(2) = 0.84, P = 0.66). Thus it appears that the GATA-4 (S377G) mutation does not play a significant role in common migraine susceptibility.

Prevalence of vertigo, dizziness, and migrainous vertigo in patients with migraine

OBJECTIVE

The aim of this study was to determine the lifetime prevalence of vertigo and dizziness in patients with migraine as compared with controls and to establish the lifetime prevalence of migrainous vertigo.

BACKGROUND

Dizziness and vertigo are relatively frequent complaints in general population; however, the prevalence of migrainous vertigo has not been extensively studied so far.

METHODS

The study included 327 migraine patients and 324 controls who do not suffer from frequent headaches. The study and control group were assessed clinically and through diagnostic workup for having vertigo, dizziness, hypotension, and sideropenic anemia.

RESULTS

Vertigo or dizziness was experienced by 51.7% of migraine patients (MVL group) and 31.5% in the control group (CVL group), P < .0001. Among the MVL group, 23.2% of patients met the criteria for migrainous vertigo. There was no difference between the MVL group and CVL group in frequency of attacks or the pattern of symptom appearance in relation to head movement. Patients in the MVL group more frequently had hypotension, P = .011. Patients with migraine with aura significantly more often had migraine attacks in association with vertigo or dizziness, P < .0001.

CONCLUSION

The lifetime prevalence of migrainous vertigo is relatively frequent in migraine patients, especially in migraine with aura.

Genetics of migraine headache in children

A family history of migraine is very frequently noted when evaluating a child for recurrent headaches. This implies an inherited or genetic basis as a component to the underlying pathophysiology. A variety of techniques have begun to elucidate this contribution, including historical observation, population-based studies including family and twin studies, gene polymorphism association studies, and specific gene identification for isolated migraine subtypes. This line of investigation should progress in the future to a better understanding of migraine and clarification of the diagnostic subtypes for a genotype-phenotype association.

Family-based analysis of serotonin transporter gene polymorphisms in migraine with and without aura

Genetic epidemiological twin studies have demonstrated a significant heritability for migraine, with > 60% of liability to migraine either with or without aura coming from additive genetic factors. Because of the essential role of serotonin in the pathophysiology and treatment of migraine, genes of the serotonin system are candidates for involvement in migraine. Consequently, we examined two functional VNTR polymorphisms in the serotonin transporter gene, the 5-HTTLPR and the intron 2 VNTR, in a sample of 212 family trios each with a proband with childhood migraine, 153 with migraine without aura (MoA) and 59 with migraine with aura (MA). For the first time, we used transmission disequilibrium test analysis with the program TDTPHASE to examine the transmission of these two markers and their haplotypes to offspring affected by migraine. We found no significant transmission distortion of any marker, with the common L allele of the 5-HTTLPR transmitted 170 times and not transmitted 178 times, and the S allele 130 vs. 122 times. Likewise, the common 12 allele of the intron 2 VNTR was transmitted 201 times and not transmitted 188 times, and the 10 allele 107 vs. 120 times. The markers were not associated with MoA and MA and none of the haplotypes was associated with overall migraine, MoA or MA. The 5-HTTLPR and the intron 2 VNTRs do not play a major role in susceptibility to migraine.

Functional polymorphisms of the 5-HT1A and 5-HT1B receptor are associated with clinical symptoms in migraineurs

Migraine is regarded as a polygenic disease and serotonergic pathways appear to play a major role in its pathogenesis. In the present study, the role of the 5-HT1A and 5-HT1B receptors in migraine was evaluated. The human 5-HT1A receptor gene transcription is modulated by a functional C-1019G promoter polymorphism. The 5-HT1B receptor is the main effector of vasoconstriction in meningeal and cerebral arteries and its functional G861C promoter polymorphism was investigated. We report a positive association of the GG genotype of the 5-HT1A promoter polymorphism with avoidance of physical activity during a migraine attack in comparison to the CC genotype (p = 0.008). Moreover, a positive association of the CC genotype of the G861C polymorphism of the 5-HT1B receptor with the reported intensity of the headache attack on the visual analogue scale was observed (CC 8.3 +/- 1.5 vs. GG 6.9 +/- 1.8; p < 0.05). An association of either polymorphism with migraine with or without aura could not be found. For the first time, our results indicate a role of allelic variation of the 5-HT1A receptor in motion related discomfort in migraineurs and a role of the 5-HT1B receptor polymorphism in headache intensity.

Influence of MTHFR Genotype on Contingent Negative Variation And MRI Abnormalities in Migraine

BACKGROUND

The MTHFR C677T genotype has been associated with increased risk of migraine, particularly of migraine with aura (MA) in selected clinical samples and with elevated homocysteine. The hyper-homocysteinemia may favor the vascular and neuronal mechanism underlying migraine, and the risk of stroke.

OBJECTIVE

The first aim of the present study was to examine the Contingent Negative Variation (CNV) amplitude and habituation pattern in a migraine sample versus non-migraine subjects, at the light of the MTHFR genotype, according to an unrelated and clinical based case-control panel. The second aim was to compare the frequency of Magnetic Resonance Imaging (MRI) subclinical brain lesions across the different C677 genotypes in the same migraine sample, selected for the young age and the absence of any cardiovascular risk factor.

METHODS

One hundred and five 18-45 year old out-patients, 90 affected by migraine without aura (MO) and 15 by MA, and 97 non-migraine healthy subjects, age and sex matched, were selected for the genetic analysis. All subjects had a common ethnic origin from Puglia. Sixty-four migraine subjects and 33 control subjects were submitted to the recording of the CNV. All migraine subjects underwent the MRI evaluation.

RESULTS

The frequency of homozygosis was 14.33% in normal subjects, versus 25.7% in MA + MO group (chi2-test: 10.80 P= .001). The frequency of homozygosis in MO patients, was 25.5% (MA versus N: chi2-test: 9 P= .003), in MA group it was 26.6%. Considering the MTHFR genotype in migraine patients and controls, the C677TT subjects exhibited a reduced habituation index of the early CNV (iCNV), in respect with both C677TC and C677CC; in the migraine group, there was a significant decrease of CNV habituation in patients with homozygosis and a positive correlation between the habituation index values and the homocysteine levels. Nineteen migraine patients exhibited subclinical brain lesions (18.05%): patients with C677T homozygosis did not exhibit a higher risk for MRI abnormalities.

CONCLUSIONS

This unrelated and clinical based case-control study showed that genetically induced hyper-homocysteinemia may favor the neuronal factors predisposing to migraine, while it does not influence the presence of subclinical vascular brain lesions probably linked with increased risk of stroke.

Interictal habituation deficit of the nociceptive blink reflex: an endophenotypic marker for presymptomatic migraine?

Habituation of the nociception-specific blink reflex (nBR) is reduced interictally in migraine patients. This could be related to the habituation deficit of evoked cortical responses, a reproducible abnormality in migraine which has a familial character, or to central trigeminal sensitization due to repeated attacks. We compared nBR habituation in healthy volunteers devoid of personal or family history of migraine (HV), in migraine without aura patients (MO) and in healthy volunteers with a family history of migraine in first degree relatives (HV-F). We elicited the nBR by stimulating the right supraorbital region with a custom-built electrode in 16 MO between attacks, 15 HV and 14 HV-F. Habituation was measured as the percentage area-under-the-curve decrease in 10 consecutive blocks of five averaged rectified responses. nBR habituation was clearly reduced in MO and HV-F compared to HV. Percentage area under the curve decreased between the 1st and the 10th block by 55.01% in HV, 25.71% in MO (P = 0.001) and 26.73% in HV-F (P = 0.043). HV-F had the most pronounced abnormality with potentiation instead of habituation in the second block. We found a positive intraindividual correlation between attack frequency and habituation in MO (r = 0.621; P = 0.010). Migraine patients have interictally a deficient habituation of the nBR which is inversely related to attack frequency, suggesting that it is not due to trigeminal sensitization. Surprisingly, the most pronounced habituation deficit is found in asymptomatic individuals with a family history of migraine. Deficient nBR habituation could thus be a trait marker for the genetic predisposition to migraine.

Endothelial nitric oxide synthase (Glu298Asp) polymorphism is an independent risk factor for migraine with aura

OBJECTIVE

The aim of the present study was to evaluate whether the functional endothelial nitric oxide synthase (eNOS) Glu298Asp polymorphism, which has been demonstrated to decrease the endothelial NOS activity, might be a risk factor for migraine.

BACKGROUND

It has widely demonstrated that nitric oxide (NO) is involved in migraine pathogenesis. Several genetic risk factors have been associated with migraine, but no study has unraveled a possible relationship between migraine and eNOS Glu298Asp. Methods.-One hundred fifty-six migraine patients and 125 healthy nonheadache volunteers entered the study. Demographic and clinical characteristics were carefully recorded, and a neurological workup was performed.

RESULTS

eNOS AspAsp homozygous patients had a 3-fold time risk for migraine with aura (MA) when compared to migraine without aura (MO) patients (OR-3.02, 95% CI-1.21 to 7.51), and more than 2-fold time increased risk when compared to control subjects (OR-2.21, 95% CI-1.00 to 5.04). In migraine patients, no difference in age at onset, mean attack's intensity, family history for any of the studied comorbidities, or the presence of comorbidities was found in eNOS AspAsp homozygous compared to eNOS GluGlu or eNOS GluAs carriers.

CONCLUSIONS

Homozygous Asp298, a common variant of the eNOS gene, is an independent risk factor for MA in this study population.

The role of vascular and hormonal genes in migraine susceptibility

Migraine is a primary headache disorder that involves both genetic and environmental components. Migraine is considered to be a polygenic disorder with a number of susceptibility genes having a minor but nonetheless significant impact on susceptibility. Migraine candidate gene studies have concentrated mainly on genes involved in neurotransmitter pathways, however evidence also exists for a role for alterations in vascular and hormonal function in migraine susceptibility. We present here a mini-review of genetic studies, investigating the potential role of vascular and hormonal gene variants, and discuss how vascular and hormonal dysfunction may impact on migraine susceptibility. We propose that the potential role of vascular and hormonal genes in this disorder warrants further investigation.

Endothelin Receptor A -231 G>A Polymorphism: No Linkage to Primary Pediatric Headache

OBJECTIVE

To assess whether the biallelic -231 G>A polymorphism of the endothelin type A receptor (EDNRA) gene, previously shown to be a marker of increased risk for developing migraine, has a role in the susceptibility to primary pediatric headache.

BACKGROUND

Several studies suggest that endothelin has a role in migraine. A recent association study has shown that the biallelic -231 G>A polymorphism of the EDNRA gene is associated to migraine in an elderly population.

METHODS

A total of 126 consecutive unrelated pediatric patients affected by primary headache, classified according to the International Headache Society criteria in migraine (migraine with aura, n = 3; migraine without aura, n = 80), and tension-type headache (episodic tension-type headache, n = 36; chronic tension-type headache, n = 7) patients, were recruited to the study. Sixty-seven healthy blood donors were used as a control group. Genomic DNA was extracted from buccal swabs or blood samples and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for the above-mentioned polymorphism. Allele and genotype frequencies for primary headache patients were analyzed in comparison with the control group.

RESULTS

No significant differences were found in the distribution of the EDNRA -231 G>A polymorphic variant when considering both genotype (migraine chi2 = 2.78, P = .25; tension-type headache chi2 = 3.58, P = .17) and allelic frequencies (migraine chi2 = 1.48, P = .22; tension-type headache chi2 = 0.39, P = .56). Furthermore, no significant genotype-related difference was found in relation to clinical features, such as age at onset, frequency, and length of the attacks.

CONCLUSIONS

Our study shows that the -231 G>A polymorphism in the EDNRA gene is neither associated with primary juvenile headache nor significantly correlated with main clinical features characteristic of the headache pathology in pediatric settings.

No role for estrogen receptor 1 gene intron 1 Pvu II and exon 4 C325G polymorphisms in migraine susceptibility

Background

We have previously reported an association between the estrogen receptor 1 (ESR1) gene exon 8 G594A polymorphism and migraine susceptibility in two independent Australian cohorts. In this paper we report results of analysis of two further single nucleotide polymorphisms (SNPs) in the ESR1 gene in the same study group, the T/C Pvu II SNP in intron 1 and the C325G SNP in exon 4, as well as results of linkage disequilibrium (LD) analysis on these markers.

Methods

We investigated these variants by case-control association analysis in a cohort of 240 migraineurs and 240 matched controls. The SNPs were genotyped using specific restriction enzyme assays. Results were analysed using contingency table methods incorporating the chi-squared statistic. LD results are presented as D' statistics with associated P values.

Results

We found no evidence for association of the Pvu II T/C polymorphism and the C325G polymorphism and migraine susceptibility and no evidence for LD between these two SNPs and the previously implicated exon 8 G594A marker.

Conclusion

We have found no role for the polymorphisms in intron 1 and exon 4 with migraine susceptibility. To further investigate our previously implicated exon 8 marker, we suggest the need for studies with a high density of polymorphisms be undertaken, with particular focus on markers in LD with the exon 8 marker.

Investigating the Association Between Notch3 Polymorphism and Migraine

OBJECTIVE

The aim of the present study was to evaluate whether the functional Notch3 polymorphism T6746C, which is not causative for cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), might be a risk factor for migraine.

BACKGROUND

It has been recently demonstrated that migraine is characterized by subclinical brain infarctions and white matter lesions. Several genetic risk factors have been associated with migraine, but no study has unraveled a possible relationship between migraine and Notch3, which is involved in vascular damage. Mutations in Notch3 gene have been demonstrated to be pathogenetic for CADASIL, a small vessel disease of the brain characterized by migraine.

METHODS

A total of 156 migraine patients and 128 nonheadache healthy volunteers entered the study. Demographic and clinical characteristics were carefully recorded, and a neurological work-up was performed. Moreover, each subject underwent a blood sampling for Notch3 genotype determination.

RESULTS

Notch3 genotypes as well as allele frequencies did not differ in migraine patients compared to controls, even adjusting for the presence of possible confounds. No difference has been found either in migraine patients with aura or in those without aura.

CONCLUSIONS

These findings support the view that functional polymorphism T6746C in Notch3 gene is not involved in increasing the risk of migraine or migraine subtypes.

A Highly Polymorphic Poly-Glutamine Stretch in the Potassium Channel KCNN3 in Migraine

OBJECTIVE

The present study is designed to further elucidate the molecular genetic basis of migraine with and without aura.

BACKGROUND

Migraine is a common disease of as yet unknown etiology. Interest in ion channels in migraine has been spurred by molecular genetic findings in familial hemiplegic migraine, since familial hemiplegic migraine type 1 is caused by mutations in the calcium channel gene CACNA1A.

METHODS

Given this role of ion channels in migraine, we assessed the potassium channel KCNN3 as a candidate gene for common migraine. We analyzed the highly polymorphic repeat region coding for a poly-glutamine stretch, which constitutes part of the cytoplasmic tail of the channel protein.

RESULTS

We found an excess of the allele coding for 15 poly-glutamines in migraine patients.

CONCLUSIONS

The potassium channel KCNN3 may thus be of pathophysiological importance in migraine with and without aura.

Lack of interaction between a polymorphism in the dopamine D2 receptor gene and the clinical features of migraine

The purpose of this study was to evaluate whether a particular genotype of the dopamine D2 receptor (DRD2) gene would affect the clinical features of migraine. In a group of 118 migraineurs (55 migraine with aura and 63 migraine without aura patients), we tested the association of the biallelic C/T NcoI DRD2 polymorphism with several characteristics of the disease. Genotype and allele frequencies resulted similarly distributed in migraine with aura and migraine without aura patients (chi2 = 1.58, P = 0.45 and chi2 = 0.09, P = 0.77, respectively). The different DRD2 genotypes (C/C, C/T and T/T) had no significant effects on age at onset of migraine, presence of premonitory phenomena, frequency of headache attacks, associated symptoms, psychological features and quality of life of our migraine patients. The results of our study do not support a role for the DRD2 gene in modifying the clinical features of migraine.

Monoamine oxidases A and B gene polymorphisms in migraine patients

Abnormal cortical activity and brainstem functioning are considered the possible etiopathogenetic factors of migraine. Monoamine oxidase A and B (MAO-A and -B) regulate the levels of monoamine neurotransmitters, so changes in their activity could participate in migraine pathogenesis. We have investigated the possible association of MAO-A and -B alleles and haplotypes with two common types of migraine, i.e. migraine without aura (MO) and migraine with aura (MA), on the sample of 110 migraineours (80 MO and 30 MA) and 150 controls. MAO-A promoter and MAO-B intron 13 polymorphisms were genotyped by the PCR-based methods. In addition, we have reevaluated the reported association between MAO-B intron 13 polymorphism and platelet MAO-B activity. The platelet MAO-B activity was determined fluorimetrically using kynuramine as a substrate. We have found a tendency toward association of the shorter variant of MAO-A gene promoter with migraine without aura in male subjects. Regarding investigated MAO-B polymorphism, no association with migraine or with platelet MAO-B activity was found. The suggestive association of the variant in MAO-A gene with migraine is considered worthy of independent replication. On the other hand, further studies on MAO-B polymorphism in migraine do not seem promising.

Investigation of an LDLR gene polymorphism (19p13.2) in susceptibility to migraine without aura

We performed a genetic association study with the LDL receptor gene (LDLR) on chromosome 19p13.2 in 360 migraine patients, 220 with migraine without aura (MO) and 140 with migraine with aura (MA), and 200 controls, by analysing two polymorphic markers, a G142A transition in exon 10 and a triallelic (TA)n repeat in exon 18. The allelic distribution of the (TA)n polymorphism was significantly different between migraine without aura (MO) and both controls and migraine with aura (MA). We suggest a possible predisposition to MO in the studied population through this polymorphism or another polymorphism in linkage disequilibrium with (TA)n.

Glutathione S-transferase polymorphisms: susceptibility to migraine without aura

Migraine is considered to be a polygenic multifactorial disease with various environmental and genetic etiologies. We investigated glutathione S-transferase (GST) P1 Ile(105)Val, T1 and M1 polymorphisms in 174 Japanese headache sufferers and 372 Japanese controls. The headache group consisted of 38 cases of migraine with aura, 95 migraine without aura (MWOA) and 41 tension-type headache sufferers. The M1 homozygous deletion genotype was significantly higher in MWOA (64%) compared with controls (46%; p < 0.01; odds ratio = 2.18, 95% confidence interval: 1.32-3.61, adjusted for age and gender). In a comparison of the current smokers, the M1 null frequencies in MWOA were further increased. GSTM1 may be one of the genetic risk factors for MWOA in the Japanese population.