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.

Hereditary channelopathies in neurology

Ion channelopathies are caused by malfunction or altered regulation of ion channel proteins due to hereditary or acquired protein changes. In neurology, main phenotypes include certain forms of epilepsy, ataxia, migraine, neuropathic pain, myotonia, and muscle weakness including myasthenia and periodic paralyses. The total prevalence of monogenic channelopathies in neurology is about 35:100,000. Susceptibility-related mutations further increase the relevance of channel genes in medicine considerably. As many disease mechanisms have been elucidated by functional characterization on the molecular level, the channelopathies are regarded as model disorders for pathogenesis and treatment of non-monogenic forms of epilepsy and migraine. As more than 35% of marketed drugs target ion channels, there is a high chance to identify compounds that counteract the effects of the mutations.

Two-stage case-control association study of dopamine-related genes and migraine

BACKGROUND

We previously reported risk haplotypes for two genes related with serotonin and dopamine metabolism: MAOA in migraine without aura and DDC in migraine with aura. Herein we investigate the contribution to migraine susceptibility of eight additional genes involved in dopamine neurotransmission.

METHODS

We performed a two-stage case-control association study of 50 tag single nucleotide polymorphisms (SNPs), selected according to genetic coverage parameters. The first analysis consisted of 263 patients and 274 controls and the replication study was composed by 259 cases and 287 controls. All cases were diagnosed according to ICHD-II criteria, were Spanish Caucasian, and were sex-matched with control subjects.

RESULTS

Single-marker analysis of the first population identified nominal associations of five genes with migraine. After applying a false discovery rate correction of 10%, the differences remained significant only for DRD2 (rs2283265) and TH (rs2070762). Multiple-marker analysis identified a five-marker T-C-G-C-G (rs12363125-rs2283265-rs2242592-rs1554929-rs2234689) risk haplotype in DRD2 and a two-marker A-C (rs6356-rs2070762) risk haplotype in TH that remained significant after correction by permutations. These results, however, were not replicated in the second independent cohort.

CONCLUSION

The present study does not support the involvement of the DRD1, DRD2, DRD3, DRD5, DBH, COMT, SLC6A3 and TH genes in the genetic predisposition to migraine in the Spanish population.

[Regulatory effects of Wuzhuyutang (Evodiae prescription) and its consisting herbs on TPH2 promoter]

OBJECTIVE

To screen the active component of Wuzhuyutang (WZYT, Evodiae prescription) and investigate the regulatory effects of the components in WZYT on the TPH2 promoter, and to explore the possible molecular mechanism of WZYT on migraine.

METHOD

By transfecting a TPH2 promoter regulating Red Fluorescent Protein expressing plasmid into PC12 cell, the global fluorescence intensities and calculations of fluorescent cells after components treatment were statistically evaluated.

RESULT

Different regulatory effects of different components in WZYT with different concentrations on TPH2 promoter were observed.

CONCLUSION

TPH2 promoter drove Red Fluorescent Protein expressing cell line can be used as system screening components targeting TPH2 promoter activity. The possible mechanism of WZYT on migraine may due to its stimulating effects on TPH2 promoter, and promote the synthesis and release of 5-HT in cerebral.

[TRPV1 receptor as a therapeutical target for the treatment of migraine]

Migraine is a disorder that involves throbbing head pain with increased sensory sensitivity to light, sound, and head movement. Although the pathophysiology of migraine is still obscure, the excitement of the trigeminovascular system followed by the neurogenic inflammation in the dura mater has been implicated in the development of headaches. In addition, the TRPV1 receptor, which is known as one of the nociceptive receptors has recently been shown to express in the dura mater. These findings indicate an association between the TRPV1 receptor and migraine headaches. Furthermore, it suggests of a possibility that the TRPV1 receptor can act as a new therapeutic target for migraine. First, we reviewed the pathophysiology of migraine and the function of the TRPV1 receptor at first. Next, we introduce the possible therapeutic approaches for the application of this receptor for treating migraine; these approaches include regulation of neurotransmitter release via the TRPV1 receptor, regulation of pain conduction pathways via the TRPV1 receptor, and the regulation of the expression of the TRPV1 receptor.

Migraine with and without headache

Transient visual and neurological episodes are relatively common and can occur for the first time in middle and old age. In many cases these transient events are migraine auras. An aura is a transient, stereotypical, visual or neurological episode usually lasting 4 to 60 minutes in duration. Migraine is usually, but not always, associated with headache and can be accompanied by systemic and autonomic symptoms. Diagnosis is dependent on International Headache Society criteria. The pathophysiology is believed to involve neurovascular mechanisms. There is a hereditary component to migraine. When migraine auras occur in the absence of headache they are termed acephalgic migraines. Late onset migraine accompaniment is an acephalgic migraine that presents in middle-aged and older adults. It is usually benign. Migraines can be mimicked by other more serious conditions. Most patients with a stable migraine pattern and normal neurological evaluation do not require further testing. Some patients with atypical presentation, older age, or suspected secondary causes need further investigation.

The borderland of epilepsy: clinical and molecular features of phenomena that mimic epileptic seizures

Paroxysmal losses of consciousness and other episodic neurological symptoms have many causes. Distinguishing epileptic from non-epileptic disorders is fundamental to diagnosis, but even this basic dichotomy is often challenging and is certainly not new. In 1907, the British neurologist William Richard Gowers published his book The Border-land of Epilepsy in which he discussed paroxysmal conditions "in the border-land of epilepsy-near it, but not of it" and their clinical differentiation from epilepsy itself. Now, a century later, we revisit the epilepsy borderland, focusing on syncope, migraine, vertigo, parasomnias, and some rarer paroxysmal disorders. For each condition, we review the clinical distinction from epileptic seizures. We then integrate current understanding of the molecular pathophysiology of these disorders into this clinical framework. This analysis shows that, although the clinical manifestations of paroxysmal disorders are highly heterogeneous, striking similarities in molecular pathophysiology are seen among many epileptic and non-epileptic paroxysmal phenomena.

Deciphering migraine

Migraine is an episodic headache disorder affecting as many as 10% of people worldwide. Familial hemiplegic migraine (FHM) is an autosomal dominant subtype of severe migraine accompanied by visual disturbances known as aura. Migrainous aura is caused by cortical spreading depression (CSD) - a slowly advancing wave of tissue depolarization in the cortex. More than half of FHM cases are caused by mutations in the CACNA1A gene, which encodes a neuronal Cav2.1 Ca2+ channel, resulting in increased Ca2+ flow into dendrites and excessive release of the excitatory neurotransmitter glutamate. In this issue of the JCI, Eikermann-Haerter et al. show that transgenic mice with FHM-associated mutations in Cacna1a have increased susceptibility to CSD compared with wild-type animals, likely due to augmentation of excitatory neurotransmission (see the related article beginning on page 99). Additional as-yet-undefined channel mutations may similarly render the migraine brain more susceptible to the initiation of CSD, with implications not only for the genesis of migraine but also for the hypoxic injury that accompanies its worst manifestation, complicated migraine.

Migraine and vasodepressor syncope in a large family

We evaluated a 47-year-old woman for recurrent migraine and syncope. The patient had 7 children (not examined by the authors), all of whom also experienced migraine and syncope. The patient's father, now deceased, had reportedly experienced migraine and episodes of feeling faint. All 5 of the patient's siblings reported migraine, and 4 of the 5 reported syncope. The case of our patient, which we discuss herein, suggests a genetic link between these 2 conditions, both of which include vascular dysregulation in their pathogenesis. To our knowledge, the medical literature contains no previous description of familial associations of combined migraine and syncope.

Migraine and stroke: the role of oral contraceptives

The use of oral contraceptives (OCs) confers an increased risk for ischaemic stroke (IS). This risk slightly decreases, but remains significant, if low-dose formulations are used, particularly if other risk factors, such as hypertension or smoking, are associated. Some inherited prothrombotic conditions (e.g., Factor V Leiden, G20210A prothrombin or methylenetetrahydrofolate reductase C677T polymorphism) could also greatly increase the IS risk if present in OC users. Migraine, particularly with aura, is an independent risk factor for IS, and the patient's IS risk is probably affected by other individual risk factors (e.g., age, genetic predisposition to thrombosis, presence of patent foramen ovale or enhanced platelet aggregation) which seem to be over-represented in migraine patients. IS risk among migraineurs is further increased when OCs are currently used and can become very high if associated with smoking. Consequently, in 2004 the WHO stated in its 'Medical Eligibility Criteria for Contraceptive Use' that women suffering from migraine with aura at any age should never use OCs. Moreover, since the exposure to the effects of OCs may greatly increase the IS risk in some migraine subpopulations with specific personal characteristic, testing for these risk factors may allow for more accurate stratification of the population at risk before long-term use of OCs is prescribed.

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.

Assessing quality and normalization of microarrays: case studies using neurological genomic data

BACKGROUND

Genomic analysis using microarray tools has the potential benefit of enhancing our understanding of neurological diseases. The analysis of these data is complex due to the large amount of data generated. Many tools have been developed to assist with this, but standard methods of analysis of these tools have not been established.

OBJECTIVE

This study analyzed the sensitivity and specificity of different analytical methods for gene identification and presents a standardized approach.

METHODS

Affymetrix HG-U133 plus 2.0 microarray datasets from two neurological diseases - chronic migraine and new-onset epilepsy - were used as source data and methods of analysis for normalization of data and identification of gene changes were compared. Housekeeping genes were used to identify non-specific changes and gender related genes were used to identify specific changes.

RESULTS

Initial normalization of data revealed that 5-10% of the microarray were potential outliers due to technical errors. Two separate methods of analysis (dChip and Bioconductor) identified the same microarray chips as outliers. For specificity and sensitivity testing, performing a per-gene normalization was found to be inferior to standard preprocessing procedures using robust multichip average analysis.

CONCLUSIONS

Technical variation in microarray preprocessing may account for chip-to-chip and batch-to-batch variations and outliers need to be removed prior to analysis. Specificity and sensitivity of the final results are best achieved following this identification and removal with standard genomic analysis techniques. Future tools may benefit from the use of standard tools of measurement.

[Relationship between P-type Na+ -K+ -Atpase and migraine: an experimental study with rats]

OBJECTIVE

To investigate the role of P-type Na+ -K+ -ATPase in the mechanism of migraine.

METHODS

nitroglycerin induced migraine Twenty Sprague-Dawley rats, 10 male and 10 female, were randomly divided into 2 groups: model group, undergoing subcutaneous injection of nitroglycerin 10 mg/kg once a week for 4 weeks so as to establish migraine model, and control group, undergoing subcutaneous injection of normal saline. Then the rats were killed with their trigeminal ganglia, trigeminocervical complex, and cortex of frontal lobe taken out. RT-PCR and Western-blotting were used to detect the mRNA and protein expression of P-type Na+ -K+ -ATPase. Immuno-precipitation assay was conducted to observe the Na+ -K+ -ATPase activity. The concentration of intracellular Ca2+ was investigated by Fluo-3/AM fluorometric method.

RESULTS

The mRNA and protein expression levels and activity of P-type Na+ -K+ -ATPase in the trigeminal ganglion and trigeminocervical complex of the model group were 0.72 +/- 0.05, 0.59 +/- 0.05, and 5.21 +/- 0.51 respectively, and the mRNA and protein expression levels and activity of P-type Na+ -K+ -ATPase in the cortex of frontal lobe of the model group were 0.70 +/- 0.05, 0.60 +/- 0.05, and 3.61 +/- 0.49 respectively, all significantly lower than those of the control group (0.83 +/- 0.10, 0.67 +/- 0.06, 6.53 +/- 0.73, 0.81 +/- 0.08, 0.71 +/- 0.09, and 6.61 +/- 0.73 respectively, all P < 0.05). The concentration of intracellular Ca2 in trigeminal ganglion and trigeminocervical complex and the concentration of Ca2+ in the cortex of frontal lobe of the model group were 211,182 +/- 12,973 and 186,511 +/- 18,297 respectively, both significantly higher than those of the control group (135,243 +/- 18,105 and 143,289 25,175 respectively, both P < 0.01).

CONCLUSION

P-type Na+ -K+ -ATPase may infect the pathogenesis of migraine by its expression and activity.

[Migraine management: current trends and future prospects]

Despite its high prevalence and individual as well as societal burden, migraine remains underdiagnosed and undertreated. In recent years, the options for the management of migraine patients have greatly expanded. A number of drugs belonging to various pharmacological classes and deliverable by several routes are now available both for the acute and the preventive treatments of migraine. Nevertheless, disability and satisfaction remain low in many subjects because treatments are not accessible, not optimized, not effective or simply not tolerated. There is thus still considerable room for better education and for more efficient therapies. In spite of useful internationally accepted guidelines, anti-migraine treatment has to be individually tailored to each patient taking into account the migraine subtype, the ensuing disability, the patient's previous history and present expectations, and the comorbid disorders. In this article we will summarize the phenotypic presentations of migraine and review recommendations for acute and preventive treatment, highlighting recent advances which are relevant for clinical practice in terms of both diagnosis and management.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in migraine patients

BACKGROUND

The main objective of this study was to investigate the angiotensin converting enzyme (ACE) genotype as a possible risk factor for migraine (both with and without aura) compared to controls. We also wanted to examine whether a clinical response to an ACE inhibitor, lisinopril, or an angiotensin II receptor blocker, candesartan, in migraine prophylaxis was related to ACE genotype.

METHODS

347 migraine patients aged 18-68 (155 migraine without aura (MoA), 187 migraine with aura (MwA) and 5 missing aura subgroup data) and 403 healthy non-migrainous controls > 40 years of age were included in the study. A polymerase chain reaction (PCR) was performed on the genomic DNA samples to obtain the ACE insertion (I)/deletion(D) polymorphisms.

RESULTS

No significant differences between migraine patients and controls were found with regard to ACE genotype and allele distributions. Furthermore, there was no significant difference between the controls and the MwA or MoA subgroups.

CONCLUSION

In our sample there is no association between ACE genotype or allele frequency and migraine. In addition, ACE genotype in our experience did not predict the clinical response to lisinopril or candesartan used as migraine prophylactics.

[CADASIL syndrome - cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy]

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited neurodegenerative disease associated with mutations in the Notch 3 receptor on vascular smooth muscle cells. Clinically the syndrome is manifested as migraine, recurrent subcortical ischaemic events, dementia and mood disorders. CADASIL, considered one of the important causes of "subcortical vascular dementia", is relatively easy to overlook or misdiagnose if it is not taken into consideration in differential diagnosis. Diagnosis of CADASIL is established on the basis of results of skin biopsy and genetic examination. In this article we present a short review of the literature concerning pathogenesis and clinical presentation of the syndrome and provide recommendations for detection, diagnosis and management strategies.

Pharmacogenetics of migraine: genetic variants and their potential role in migraine therapy

Migraine is a paroxysmal neurological disorder affecting up to 6% of males and 18% of females in the general population, and has been demonstrated to have a strong, but complex, genetic component. Genetic investigation of migraine provides hope that new targets for medications and individual specific therapy will be developed. The identification of polymorphisms or genetic biomarkers for disease susceptibility and treatment should aid in providing a better understanding of migraine pathology and, consequently, more appropriate and efficient treatment for migraineurs. In this review, we will discuss results investigating genetic biomarkers for migraine and their potential role in future therapy planning.

Human disorders caused by the disruption of the regulation of excitatory neurotransmission

The nicotinic acetylcholine receptors (nAChRs) are members of the large family of ligand-gated ion channels, and are constituted by the assembly of five subunits arranged pseudosymmetrically around the central axis that forms a cation-selective ion pore. They are widely distributed in both the nervous system and non-neuronal tissues, and can be activated by endogenous agonists such as acetylcholine or exogenous ligands such as nicotine. Mutations in neuronal nAChRs are found in a rare form of familial nocturnal frontal lobe epilepsy (ADNFLE), while mutations in the neuromuscular subtype of the nAChR are responsible for either congenital myasthenia syndromes (adult subtype of neuromuscular nAChR) or a form of arthrogryposis multiplex congenita type Escobar (fetal subtype of neuromuscular nAChR).

Familial clustering of migraine, episodic vertigo, and Ménière's disease

OBJECTIVE

To evaluate the association between migraine, episodic vertigo, and Ménière's disease in families.

STUDY DESIGN

Clinical report.

SETTING

University Neurotology Clinic.

PATIENTS

Index patients identified with Ménière's disease and migraine and their family members.

INTERVENTION

Structured interview to assess a diagnosis of migraine, episodic vertigo, and Ménière's disease in 6 families. Genotyping was performed on 3 sets of twins to analyze monozygosity or dizygosity.

MAIN OUTCOME MEASURES

Clinical history of migraine, episodic vertigo, and Ménière's disease.

RESULTS

Six index patients and 57 family members were interviewed either by a senior neurologist in person or over the phone by a trained study coordinator. An additional 6 family members completed questionnaires by mail. All 6 index patients had Ménière's disease and migraine. Twenty-six (41%) of the 63 relatives met International Classification of Headache Disorders II criteria for migraine headaches. Thirteen (50%) of these 26 experienced migraine with aura. Three others experienced typical aura without headache. Seventeen (27%) of 63 family members experienced recurrent spells of spontaneous episodic vertigo. There was one twin pair in each of 3 families; 2 pairs were monozygotic and one was dizygotic. In each twin pair, one twin had migraine and Ménière's disease, whereas the other experienced migraine and episodic vertigo without auditory symptoms.

CONCLUSION

The frequent association of episodic vertigo, migraine, and Ménière's disease in closely related individuals, including identical twins supports the heritability of a migraine-Ménière's syndrome, with variable expression of the individual features of hearing loss, episodic vertigo, and migraine headaches.

[Migraine--mechanisms and consequences for treatment]

BACKGROUND

Migraine is a common headache syndrome. The understanding of processes in the brain during a migraine attack has increased significantly during recent years.

MATERIAL AND METHODS

The article is based on literature retrieved from PubMed, and on own knowledge of older and more recent migraine literature.

RESULTS AND INTERPRETATION

Patients with migraine probably have increased cortical excitability. Attacks may be initiated by the neurophysiological phenomenon "cortical spreading depression". This may again lead to meningeal inflammation and irritation of pain-sensitive fibres in the trigeminal nerve. There is compelling evidence that an episodic dysfunction of the brain stem plays an important role, either as a primary generator of or a secondary contributor to, migraine attacks. Patients often report allodynia as an expression for central sensitization. Activity in pain-modulating mechanisms is disturbed, and serotonin agonists efficiently stop attacks. The tendency to have repetitive migraine attacks is probably due to a genetic predisposition.

Prevalence, segregation, and phenotype of the mitochondrial DNA 3243A>G mutation in children

OBJECTIVE

We studied the prevalence, segregation, and phenotype of the mitochondrial DNA 3243A>G mutation in children in a defined population in Northern Ostrobothnia, Finland.

METHODS

Children with diagnoses commonly associated with mitochondrial diseases were ascertained. Blood DNA from 522 selected children was analyzed for 3243A>G. Children with the mutation were clinically examined. Information on health history before the age of 18 years was collected from previously identified adult patients with 3243A>G. Mutation segregation analysis in buccal epithelial cells was performed in mothers with 3243A>G and their children whose samples were analyzed anonymously.

RESULTS

Eighteen children were found to harbor 3243A>G in a population of 97,609. A minimum estimate for the prevalence of 3243A>G was 18.4 in 100,000 (95% confidence interval, 10.9-29.1/100,000). Information on health in childhood was obtained from 37 adult patients with 3243A>G. The first clinical manifestations appearing in childhood were sensorineural hearing impairment, short stature or delayed maturation, migraine, learning difficulties, and exercise intolerance. Mutation analysis from 13 mothers with 3243A>G and their 41 children gave a segregation rate of 0.80. The mothers with heteroplasmy greater than 50% tended to have offspring with lower or equal heteroplasmy, whereas the opposite was true for mothers with heteroplasmy less than or equal to 50% (p = 0.0016).

INTERPRETATION

The prevalence of 3243A>G is relatively high in the pediatric population, but the morbidity in children is relatively low. The random genetic drift model may be inappropriate for the transmission of the 3243A>G mutation.

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.

[P/Q-type voltage-dependent calcium channels in neurological disease]

INTRODUCTION

Voltage-dependent calcium channels (VDCC) are hetero-multimeric complexes that mediate calcium influx into cells in response to changes in membrane potential. The alpha1A subunit, encoded by the CACNA1A gene, is the pore-forming structure specific to the neuronal P/Q-type voltage-dependent calcium channels (P/QCC), present exclusively in neurons. The ancillary subunits beta, alpha2delta and gamma, which are common to other VDCC, modulate alpha1A activity. P/QCC are involved in neuronal plasticity and survival, and mediate fast neurotransmission in the central and peripheral nervous system. Their highest levels of expression are found in the Purkinje cell layer of the cerebellum and in the hippocampus.

METHODS

Congenital and acquired disturbances of the P/QCCs lay behind some neurological diseases, such as spinocerebellar ataxia type 6, episodic ataxia type 2 and paraneoplastic cerebellar degeneration; familial hemiplegic migraine; generalized convulsive epilepsy, generalized absence epilepsy and myasthenic syndrome of Lambert-Eaton.

CONCLUSION

In this article, the structure and modulation of normal P/QCCs, and the neurological diseases caused by disturbances in these are reviewed. Electrophysiological characterization of mutated P/QCCs has yielded decreased calcium conductance in every case, compared with wild type channels. Research about calcium channelopathies should clarify how altered channel function produces disease and lead to new treatments for these conditions.

Association between a polymorphism in the lymphotoxin-a promoter region and migraine

OBJECTIVE

The aim of this study was to determine whether polymorphisms in the lymphotoxin (LTA)-tumor necrosis factor (TNF) region are associated with the risk of migraine.

BACKGROUND

Previous studies concerning the role of TNFalpha in migraine have provided conflicting results. It has been reported that LTA could be a susceptibility gene in migraine. It is possible that the TNFalpha polymorphism associated with migraine is in linkage disequilibrium with other functional polymorphisms that influence migraine risk. Moreover, there are significant differences among the allele frequencies of TNF gene variants among populations from different ethnic groups.

METHODS

In a case-control study, including 439 migraine patients and 382 controls, we examined the association between 15 single nucleotide polymorphisms in the coding and promoter regions of LTA and TNFalpha genes, which are located within the 22 kb around TNF and the risk of migraine. We performed a chromatin immunoprecipitation (ChIP) assay and an electrophoretic mobility shift assay (EMSA) to identify differential protein-DNA binding of LTA-294.

RESULTS

Homozygosity for the LTA-294C allele was significantly associated with an increased risk of migraine compared with CT/TT carriers (corrected P= .005, odds ratio [OR]= 1.7, 95% confidence interval [CI] 1.3-2.3). Haplotype TGAAC was found to be significantly associated with a protective effect against migraine (P= .0005, Bonferroni corrected P= .003, OR = 0.7, 95% CI 0.5-0.8). There was no differential protein-DNA binding pattern in both EMSA and ChIP assays.

CONCLUSIONS

We found that the LTA haplotypes were associated with migraine among Koreans and that the best marker for this is the LTA-294 T/C polymorphism. Our results indicate that these associations should be defined in the context of the involvement of other genetically linked region, such as human leukocyte antigen (HLA) loci.

A pharmacogenomic evaluation of migraine therapy

Migraine is a common idiopathic primary headache disorder with significant mental, physical and social health implications. Accompanying an intense unilateral pulsating head pain other characteristic migraine symptoms include nausea, emesis, phonophobia, photophobia and in approximately 20-30% of migraine cases, neurologic disturbances associated with the aura phase. Although selective serotonin (5-HT) receptor agonists (i.e., 5-HT(1B/1D)) are successful in alleviating migrainous symptoms in < or = 70% of known sufferers, for the remaining 30%, additional migraine abortive medications remain unsuccessful, not tested or yet to be identified. Genetic characterization of the migrainous disorder is making steady progress with an increasing number of genomic susceptibility loci now identified on chromosomes 1q, 4q, 5q, 6p, 11q, 14q, 15q, 17p, 18q, 19p and Xq. The 4q, 5q, 17p and 18q loci involve endophenotypic susceptibility regions for various migrainous symptoms. In an effort to develop individualized pharmacotherapeutics, the identification of these migraine endophenotypic loci may well be the catalyst needed to aid in this goal. In this review the authors discuss the present treatment of migraine, known genomic susceptibility regions and results from migraine (genetic) association studies. The authors also discuss pharmacogenomic considerations for more individualized migraine prophylactic treatments.

Genetic association study and meta-analysis of the HTR2C Cys23Ser polymorphism and migraine

The objectives of this study were to determine if the HTR2C Cys23Ser polymorphism is associated with migraine in a case-control study, and to perform a meta-analysis with present and previous available studies. The HTR2C gene is located at the Xq24-q28 chromosomal band. This band was linked to migraine with aura (MA) in two Australian families. Using the HTR2C Cys23Ser allelic variant, this gene has been ruled out as a migraine gene in 3 out of 4 studies. Only the Japanese study reported a higher risk for MA (OR=6.11; 95% CI=1.70-21.97, p trend<0.01). We performed a case-control study with 335 migraine subjects and 335 sex- and age-matched controls, and a meta-analysis pooling the results of the available data from MA subsets of patients. In the association study we found no significant differences among migraine and MA patients for this polymorphism. In the meta-analysis, under the fixed-effect model, the Ser allele did not confer higher risk for suffering MA (pooled OR=1.1; 99% CI=0.8-1.5, p=0.499). Our study did not confirm the HTR2C Cys23Ser polymorphism as a risk factor for migraine and MA.

Association of the C677T polymorphism in the MTHFR gene with migraine: a meta-analysis

There are conflicting data concerning the association between migraine and C677T polymorphism of the MTHFR gene. The C677T polymorphism reduces enzymatic capability by 50% and causes hyperhomocysteinaemia. We performed a meta-analysis of all published studies investigating the association between the MTHFR gene and migraine. Pooled odds ratios (OR) were estimated using random (RE) and fixed effects (FE) models. Among the overall 2961 migraineurs there was no significant difference compared with controls. Only in migraine with aura was the TT genotype associated with a higher risk of disease compared with the CC genotype [FE OR 1.30, 95% confidence interval (CI) 1.06, 1.58; RE OR 1.66, 95% CI 1.06, 2.59]. In the same subgroup a significant difference was observed in the comparison between TT and CT + CC genotypes (FE OR 1.32, 95% CI 1.10, 1.59; RE OR 1.63, 95% CI 1.10, 2.43). This study provides evidence for an association of the MTHFR gene only in migraine with aura.

Family-based association analysis of functional VNTR polymorphisms in the dopamine transporter gene in migraine with and without aura

Because of the role of dopamine in triggering migraine attacks, genes of the dopamine system are candidates for involvement in migraine. We examined three VNTR polymorphisms in the dopamine transporter, the 5'UTR VNTR, the intron 8 VNTR and the intron 14 VNTR, in a sample of 205 family trios. We used the transmission disequilibirium test (TDT) to examine the transmission of these three markers and their haplotypes to offspring affected by migraine. We found no significant transmission distortion of any marker. Likewise haplotypes of the three markers did not show significant overall or individual association with migraine. Finally we examined migraine with and without aura, and likewise found no association between dopamine transporter VNTRs or their haplotypes and either classification of the disease. We conclude that functional genetic variation in the dopamine transporter does not act as a significant risk factor for migraine.

Personality, health and lifestyle in a questionnaire family study: a comparison between highly cooperative and less cooperative families

The effect of nonresponse on health and lifestyle measures has received extensive study, showing at most relatively modest effects. Nonresponse bias with respect to personality has been less thoroughly investigated. The present study uses data from responding individuals as a proxy for the missing data of their nonresponding family members to examine the presence of nonresponse bias for personality traits and disorders as well as health and lifestyle traits. We looked at the Big Five personality traits, borderline personality disorder (BPD) features, attention-deficit/hyperactivity disorder, Anger, and several measures of health (Body Mass Index, migraine) and lifestyle (smoking, alcohol use). In general, outcomes tend to be slightly more favorable for individuals from highly cooperative families compared to individuals from less cooperative families. The only significant difference was found for BPD features (p = .001). However, the absolute difference in mean scores is very small, less than 1 point for a scale ranging from 0 to 72. In conclusion, survey data on personality, health and lifestyle are relatively unbiased with respect to nonresponse.

The phe-124-Cys and A-161T variants of the human 5-HT1B receptor gene are not major determinants of the clinical response to sumatriptan

BACKGROUND

The 5-HT(1B/1D) receptor agonist sumatriptan is highly effective in the treatment of migraine. However, some patients do not respond to sumatriptan or experience recurrence of the headache after initial relief. In addition, some patients report chest symptoms after the use of sumatriptan.

OBJECTIVE

To assess whether 2 genetic variants (F124C changing a phenylalanine for a cysteine and polymorphism A/T at nucleotide position -161 in the 5' regulatory region) of the 5-HT(1B) receptor play a major role in the therapeutic response to sumatriptan. The 5-HT(1B) receptor most likely mediates the therapeutic action and coronary side effects of sumatriptan, and both F124C and A-161T have relevant functional consequences on either the affinity of sumatriptan to bind to the 5-HT(1B) receptor or on receptor expression level itself, respectively.

METHOD

Genomic DNA of a relatively small but very well-characterized set of migraine patients with consistently good response to sumatriptan (n = 14), with no response (n = 12), with recurrence of the headache (n = 12), with chest symptoms (n = 13), and patients without chest symptoms (n = 27) was available for the genetic analyses and screened for the F124C variant and the A-161T polymorphism in the human 5-HT(1B) receptor gene.

RESULTS

F124C was not detected in any of the patients studied. In addition, we did not observe drastic changes in allele frequencies of the A-161T polymorphism that might hint to a causal relation with the therapeutic effect of sumatriptan.

CONCLUSION

We have not obtained any evidence that variants F124C and A-161T of the 5-HT(1B) receptor are major determinants in the clinical response to sumatriptan.

Migraine in adolescents: association with socioeconomic status and family history

OBJECTIVE

The influence of socioeconomic status on the prevalence of migraine is unknown in adolescents. Accordingly, we investigated the prevalence of migraine in a large sample of adolescents by sociodemographic features.

METHODS

A validated headache questionnaire was mailed to 120,000 households representative of the US population. All individuals in the household were interviewed (probands and their parents). We calculated sex-specific prevalence estimates of migraine in adolescents derived by age, race, urban vs rural residence, household income, region of the country, and parental status of migraine, using log-linear models.

RESULTS

A total of 32,015 adolescents were identified. Surveys were returned by 18,714 of them (58.4% response rate). The 1-year prevalence of migraine was 6.3% (5.0% in boys and 7.7% in girls). The prevalence was higher in girls than in boys older than 12 and in whites than African Americans. In families with an annual income lower than $22,500, the adjusted prevalence of migraine in adolescents without a parental history of migraine was 4.4%; in families earning $90,000 or more, it was 2.9% (OR = 0.49, 95% CI 0.38 to 0.63). In adolescents with a parental history of migraine, the prevalence in the lower vs the higher income group was 8.6% vs 8.4% (OR = 0.97, 0.81 to 1.15).

CONCLUSIONS

In adolescents with family history of migraine, household income does not have a significant effect, probably because of the higher biologic predisposition. In those without a strong predisposition, household income is associated with prevalence. This suggests social causation rather than social selection, highlighting the need for exploration of environmental risk factors related to low income and migraine and the search for specific comorbidities and stressors in this group.

Migraine: a complex genetic disorder

Although family and twin studies show that there is a genetic component to migraine, no genes predisposing to common forms of the disorder have been identified. The most encouraging findings have emerged from the identification of genes causing rare mendelian traits that phenotypically resemble migraine. These studies have pointed migraine research towards ion-transport genes; however, there is no direct evidence of the involvement of these genes in common forms of migraine. Family-based linkage studies have identified several chromosomal regions linked to common forms of migraine, but there is little consistency between studies. The modest success in the identification of contributing gene variants has stimulated research into more effective strategies. These include new phenotyping methods for genetic studies and new study designs-such as case-control and whole-genome association studies-to identify common variants contributing to the trait.

Association study of a functional variant in intron 8 of the dopamine transporter gene and migraine susceptibility

Migraine is a common, genetically influenced neurovascular disorder. The dopamine transporter gene is a candidate for migraine association studies. This study tested a functionally linked variable number tandem repeat (VNTR) in intron 8 of the dopamine transporter gene (DAT(Int8)) in 550 migraine cases (401 with aura, 149 without aura) and 550 non-migraine controls. Chi-squared analysis of the DAT(Int8) revealed that the allele and genotype frequency distributions for migraine cases (including subtype analysis) and controls were not different (P > 0.1). These findings offer no evidence for an association of the DAT(Int8) with migraine with and without aura and therefore do not implicate the dopamine transporter gene as a modifier of migraine risk.

Association of progesterone receptor with migraine-associated vertigo

While migraine has been demonstrated to be familial and have genetic contributions, genome-wide linkage analyses and candidate gene studies have highlighted that migraine is genetically complex. Despite substantial efforts, no consistent replication of linkage or association has been reported for common migraine syndromes. Among the candidate genes tested for association with migraine by several groups were female sex hormone genes based on the observation of a much higher incidence of migraine in females. Migraine-associated vertigo (MAV) is a migraine syndrome also much more common in females than males. Because MAV is less common in the general population than migraine or migraine with aura, it may be a better migraine syndrome to detect susceptibility alleles. In this study, we tested the association of two female hormonal genes, progesterone receptor (PGR) and estrogen receptor (ESR1), which were previously reported to be associated with migraine in women. We typed 150 MAV subjects and 145 genomic matched control subjects. One SNP (rs1042838) within PGR, which is in high linkage disequilibrium with the functional PROGINS variant, was significantly associated with MAV (p = 0.0007). Two SNPs (rs2228480 and rs1801132) within ESR1 demonstrated no significant association. No synergistic effect between ESR1 variants and PGR variants was identified.