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

Migraine in childhood: Gender differences

Migraine is a common neurological disorder in developmental age, involving up to 20% of children and adolescents. Although gender differences in migraine epidemiology and clinical characteristics have been largely investigated in adulthood, this issue is considerably less known in pediatric patients. We aim at providing an overview of gender differences in pediatric migraine. The most recent literature was reviewed taking into account the epidemiological, pathophysiological, and clinical differences between boys and girls with migraine. Although many aspects need to undergo further investigation, we conclude that different aspects of childhood migraine syndrome may vary depending on the gender and age, especially with regard to pubertal development.

Glucose-Related Traits and Risk of Migraine—A Potential Mechanism and Treatment Consideration

Migraine and glucose-related (glycaemic) traits (fasting glucose, fasting insulin, and type 2 diabetes) are common and complex comorbid disorders that cause major economic and social burdens on patients and their families. Studies on the relationship between migraine and glucose-related traits have yielded inconsistent results. The purpose of this review is to synthesise and discuss the information from the available literature on the relationship between fasting glucose, fasting insulin, and type 2 diabetes (T2D) with migraine. Publications on migraine and fasting glucose, migraine and fasting insulin, and migraine and T2D were identified from a PubMed and Google Scholar database search and reviewed for this article. Multiple publications have suggested that the comorbidity of migraine and glucose-related traits may have a similar complex pathogenic mechanism, including impaired glucose homeostasis, insulin resistance, reduced cerebrovascular reactivity, abnormal brain metabolism, shared genetic factors, neurotransmitters, and sex hormones. Furthermore, several studies have found a bi-directional link between migraine with insulin resistance and T2D. There is strong evidence for a biological association between migraine headache and glucose-related traits, and burgeoning evidence for shared genetic influences. Therefore, genetic research into these comorbid traits has the potential to identify new biomarkers and therapeutic targets and provide biological insight into their relationships. We encourage healthcare professionals to consider the co-occurrence of migraine with glucose-related traits in the evaluation and treatment of their patients.

Identification of Constituents and Exploring the Mechanism for Toutongning Capsule in the Treatment of Migraine

Toutongning capsule (TTNC) is an effective and safe traditional Chinese medicine used in the treatment of migraine. In this present study, a multiscale strategy was used to systematically investigate the mechanism of TTNC in treating migraine, which contained UPLC-UESI-Q Exactive Focus network pharmacology and experimental verification. First, 88 compounds were identified by the UPLC-UESI-Q Exactive Focus method for TTNC. Then, the target fishing for these compounds was performed by means of an efficient drug similarity search tool. Third, a series of network pharmacology experiments were performed to predict the key compounds, targets, and pathways. They were protein-protein interaction (PPI), KEGG pathway enrichment analysis, and herbs-compounds-targets-pathways (H-C-T-P) network construction. As a result, 18 potential key compounds, 20 potential key targets, and 6 potential signaling pathways were obtained for TTNC in treatment with migraine. Finally, molecular docking and experimental were carried out to verify the key targets. In short, the results showed that TTNC is able to treat migraine through multiple components, multiple targets, and multiple pathways. This work may provide a theoretical basis for further research on the molecular mechanism of TTNC in the treatment of migraine.

Sex hormone-related polymorphisms in endometriosis and migraine: A narrative review

Some evidence indicates endometriosis and migraine have a common genetic predisposition in sex-hormone genes, which could have important implications for the treatment of these two heterogenous conditions. To date, the genes responsibility remains unknown. Based on the biological hypothesis that polymorphisms of genes involved in sex-hormone pathways may influence estrogen levels and phenotypes of both disorders, we did a literature search for candidate sex-hormone genes and genes involved in the metabolism of estradiol. The aim was to review the evidence for shared sex-hormone-related polymorphisms between endometriosis and migraine and provide an exhaustive overview of the current literature. We included case-control studies investigating associations between candidate sex-hormone-related genes and the disorders endometriosis and migraine, respectively. Results showed three overlapping sex-hormone-associated polymorphisms in estrogen receptor genes that are associated with both conditions. To confirm possible associations with other sex-hormone genes, larger studies are needed.

Going Deep into Synaptic Vesicle Machinery Genes and Migraine Susceptibility - A Case-Control Association Study

OBJECTIVE

A number of observations, including among our study population, have implicated variants in the syntaxin-1A, a component of the synaptic vesicles, in migraine susceptibility. Therefore, we hypothesize that variants in other components of the vesicle machinery are involved in migraine.

BACKGROUND

Migraine is a common and complex neurologic disorder that affects approximately 15-18% of the general population. The exact cause of migraine is unknown; however, genetic studies have made possible substantial progress toward the identification of underlying molecular pathways. Neurotransmitters have been for long considered to have a key role in migraine pathophysiology; so we investigated common variants in genes involved in the synaptic vesicle machinery and their impact in migraine susceptibility.

METHODS

We performed a case-control study comprising 188 unrelated patients with headache and 286 healthy controls in a population from the north of Portugal. Benefiting from the presence of linkage disequilibrium, we selected and genotyped 119 tagging single-nucleotide polymorphisms in 18 genes.

RESULTS

We found significant associations between single-nucleotide variants and migraine in 7 genes, SYN1, SYN2, SNAP25, VAMP2, STXBP1, STXBP5, and UNC13A, either conferring an increased risk or protection of migraine. Due to SYN1 X-chromosomal location, we performed the statistical analysis separated by gender and, in the female group, the C allele of rs5906435 increased the risk for migraine susceptibility (P = .021; OR = 1.69; 95% CI: 1.21-2.34). In contrast, the TT genotype of the same variant emerged as a potential protective factor (P = .003; OR = 0.45; 95% CI: 0.27-0.74). The SYN2 analysis supported the rs3773364's G allele (P = .014) as a risk factor for migraine, and although not statistically significant after correction, the AG genotype (P = .006; OR = 1.86; 95% CI: 1.20-2.90) reinforced the allelic findings. Additionally, we found the SNAP25-rs363039's CT genotype (P = .001; OR = 2.14; 95% CI: 1.36-3.34), the STXBP5-rs1765028's T allele (P = .041; OR = 1.46; 95% CI: 1.13-1.90), and the UNC13B-rs7851161's TT genotype (P = .001; OR = 2.14; 95% CI: 1.36-3.34) as statistically significant risk factors for migraine liability. VAMP2-rs1150's G allele revealed a risk association to migraine, not statistically significant after correction (P = .068). Additionally, we found haplotypes in SYN1, SYN2, STXBP1, and UNC13B to be associated with migraine.

CONCLUSIONS

Overall, this study provides a new insight into migraine liability, identifying possible starting points for functional studies.

Association between oestrogen receptors and female temporomandibular disorders

Objective: To evaluate if temporomandibular disorders (TMDs) are associated with genetic polymorphisms in ESR1 and ESR2, which are genes encoding oestrogen receptor alpha (ERα) and beta (ERβ). Also, we included an animal model to check if ERα and ERβ are expressed in the temporomandibular joint (TMJ) during adolescence.Materials and methods: A total of 139 teenagers and 93 adults were diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMDs). The DNA was collected and the markers ESR1 and ERS2 were genotyped. Additionally, immunohistochemistry was performed in TMJ tissues from female Wistar rats during puberty. All data were submitted to statistical analysis with confidence interval of 95%.Results: Teenagers presented more disc displacement and arthralgia than adults (p < .05). The genetic polymorphism rs1256049 in ESR2 was associated with disc displacement (p = .040; OR = 10.50/95%CI 1.17-98.74) and arthralgia (p = .036; OR = 7.20/95%CI 1.10-46.88) in adults. The ERα and ERβ are expressed in rat TMJ tissues.Conclusions: We provide evidence that ESR2 is associated with TMD and could be a genetic marker for this condition in adult women. Furthermore, oestrogens receptors are presented in TMJ of adolescent female rats.

Menstrual Cycle and Headache in Teenagers

OBJECTIVE

This population-based study on school-aged girls aimed to estimate the rate of peri-menstrual headache, evaluate headache pain pattern during the menstrual cycle, and verify its relationships with physical, psychosocial and life-style factors.

METHODS

The students (n = 4973) fulfilled a self-administered questionnaire on demographic and behavioral characteristics, menarche, menstrual pattern and features including headache and dysmenorrhea. The prevalence of headache and the mean pain intensity score at the three menstrual cycle phases (premenstrual, menstrual, in-between period) were estimated, both overall and by gynecological year. Furthermore, the prevalence of three different patterns of headache (peri menstrual/mid-cycle/acyclic) was evaluated, together with the mean pain intensity score.

RESULTS

The overall prevalence of headache at least once at any time during the menstrual cycle was 64.4%. At multivariable logistic analysis, gynecological age (OR 1.07; 95%CI 1.03-1.12), middle social level (1.24; 1.01-1.55, compared to high social level), physical activity (0.67; 0.51-0.89), oral contraceptive use (1.34; 1.04-1.73) and dysmenorrhea (2.30; 1.54-3.42) were significantly associated with headache. Among girls with headache, 83.4% had peri-menstrual headache (44.6% premenstrual, 38.8% menstrual), 3.5% mid-cycle headache and 13.2% acyclic headache. The gynaecological age and dysmenorrhea were significantly associated with the headache pattern (p = 0.03 and p < 0.0001, respectively).

CONCLUSIONS

This study suggests that peri-menstrual headache is highly prevalent among adolescents. In girls, the headache rate linearly raises with higher gynecological age; menses-related painful syndromes, such as headache and dysmenorrhea, are strongly interrelated. The anamnesis and monitoring of menstrual health should be mandatory when taking care of girls with headache.

Investigation of polymorphisms in genes involved in estrogen metabolism in menstrual migraine

Migraine is a common, disabling headache disorder, which is influenced by multiple genes and environmental triggers. After puberty, the prevalence of migraine in women is three times higher than in men and >50% of females suffering from migraine report a menstrual association, suggesting hormonal fluctuations can influence the risk of migraine attacks. It has been hypothesized that the drop in estrogen during menses is an important trigger for menstrual migraine. Catechol-O-methyltransferase (COMT) and Cytochrome P450 (CYP) enzymes are involved in estrogen synthesis and metabolism. Functional polymorphisms in these genes can influence estrogen levels and therefore may be associated with risk of menstrual migraine. In this study we investigated four single nucleotide polymorphisms in three genes involved in estrogen metabolism that have been reported to impact enzyme levels or function, in a specific menstrual migraine cohort. 268 menstrual migraine cases and 142 controls were genotyped for rs4680 in COMT (Val158Met), rs4646903 and rs1048943 in CYP1A1 (T3801C and Ile462Val) and rs700519 in CYP19A1 (Cys264Arg). Neither genotype nor allele frequencies for the COMT and CYP SNPs genotyped were found to be significantly different between menstrual migraineurs and controls by chi-square analysis (P>0.05). Therefore we did not find association of functional polymorphisms in the estrogen metabolism genes COMT, CYP1A1 or CYP19A1 with menstrual migraine. Further studies are required to assess whether menstrual migraine is genetically distinct from the common migraine subtypes and identify genes that influence risk.

Contribution of polymorphisms in ESR1, ESR2, FSHR, CYP19A1, SHBG, and NRIP1 genes to migraine susceptibility in Turkish population

Migraine, a highly prevalent headache disorder, is regarded as a polygenic multifactorial disease. Single-nucleotide polymorphisms (SNPs) in the genes that involved in sex hormone metabolism may comprise risk for migraine, but the results of previous genetic association studies are conflicting. The aim of this study was to evaluate genetic variants in genes involved in oestrogen receptor and oestrogen hormone metabolism in a Turkish population. A total of 12 SNPs in the ESR1, ESR2, FSHR, CYP19A1, SHBG and NRIP1 genes were genotyped in 142 migraine cases and 141 nonmigraine controls, using a BioMark 96.96 dynamic array system. In addition, gene-gene interactions were analysed using generalized multifactor dimensionality reduction (GMDR) methods. According to GMDR analysis, our results indicated that there was a significant association between migraine and gene-gene interaction among the CYP19A1, FSHR, ESR1 and NRIP1. Single-gene variant analysis showed that a significant association was observed between the TT genotype of rs10046 and migraine susceptibility.When the analysis was performed only in women, the GG genotype of rs2229741 was different between migraineurs and controls.When the female migraine patients were divided into two groups, migraine related to menstruation (MRM) or migraine not related to menstruation (MNRM), GG genotype of rs726281 was significantly associated with MRM. These results suggested that rs10046 could play a potential role in migraine susceptibility in Turkish population. Also, the rare GG genotype of rs726281 appears to influence migraine susceptibility in a recessive manner in MRM subgroup of female patients. In addition, variant GG genotype of rs2229741 may reduce the risk of migraine in Turkish women.

New evidence for involvement of ESR1 gene in susceptibility to Chinese migraine

Migraine is a common and disabling nervous system disease with a significant genetic predisposition. The sex hormones play an important role in the pathogenesis of migraine. However, the conclusions of the previous genetic relation studies are conflicting. The aim of this study is to determine whether variants in genes involved in estrogen receptor and estrogen hormone metabolism are related to Chinese migraine. By employing a case-control approach, 8 SNPs in the ESR1, ESR2, and CYP19A1 genes are studied in a cohort of 494 migraine cases and 533 controls. In addition, genotyping is performed using Sequenom MALDI-TOF mass spectrometry iPLEX platform. Univariate and multivariate analyses are carried out by logistic regression. The corresponding haplotypes are studied with the Haploview software and gene-gene interaction is assessed using the Generalized Multifactor Dimensionality Reduction (GMDR) analysis. There are significant differences in allelic distributions for rs2234693 and rs9340799 in ESR1 gene between patients with migraine and control subjects. Univariate logistic analysis shows that rs2234693 and rs9340799 are risk factors for migraine, but multivariate analysis reveals that only rs2234693 is significant associated with migraine. In the subgroup analysis, rs2234693 in ESR1 gene is found associated with menstrually related migraine. Further haplotypic analysis shows that rs2234693-rs9340799 TA haplotype serves as risk haplotype for migraine. The GMDR analysis identifies rs2234693 in ESR1 alone to be a crucial candidate in migraine susceptibility. This study is in agreement with the previous studies that variants in the ESR1 gene are associated with migraine suggesting that it plays a role in the migraine process.

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.

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.

Migraine genetics: current findings and future lines of research

In the last two decades, migraine research has greatly advanced our current knowledge of the genetic contributions and the pathophysiology of this common and debilitating disorder. Nonetheless, this knowledge still needs to grow further and to translate into more effective treatments. To date, several genes involved in syndromic and monogenic forms of migraine have been identified, allowing the generation of animal models which have significantly contributed to current knowledge of the mechanisms underlying these rare forms of migraine. Common forms of migraine are instead posing a greater challenge, as they may most often stem from complex interactions between multiple common genetic variants, with environmental triggers. This paper reviews our current understanding of migraine genetics, moving from syndromic and monogenic forms to oligogenic/polygenic migraines most recently addressed with some success through genome-wide association studies. Methodological issues in study design and future perspectives opened by biomarker research will also be briefly addressed.

Studies on the pathophysiology and genetic basis of migraine

Migraine is a neurological disorder that affects the central nervous system causing painful attacks of headache. A genetic vulnerability and exposure to environmental triggers can influence the migraine phenotype. Migraine interferes in many facets of people's daily life including employment commitments and their ability to look after their families resulting in a reduced quality of life. Identification of the biological processes that underlie this relatively common affliction has been difficult because migraine does not have any clearly identifiable pathology or structural lesion detectable by current medical technology. Theories to explain the symptoms of migraine have focused on the physiological mechanisms involved in the various phases of headache and include the vascular and neurogenic theories. In relation to migraine pathophysiology the trigeminovascular system and cortical spreading depression have also been implicated with supporting evidence from imaging studies and animal models. The objective of current research is to better understand the pathways and mechanisms involved in causing pain and headache to be able to target interventions. The genetic component of migraine has been teased apart using linkage studies and both candidate gene and genome-wide association studies, in family and case-control cohorts. Genomic regions that increase individual risk to migraine have been identified in neurological, vascular and hormonal pathways. This review discusses knowledge of the pathophysiology and genetic basis of migraine with the latest scientific evidence from genetic studies.

Migraine genes and the relation to gender

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

Association of oestrogen-receptor gene (ESR1) polymorphisms with migraine in the large Norfolk Island pedigree

Background

Oestrogen receptor 1 ( ESR1) is located in region 6q25.1 and encodes a ligand-activated transcription factor composed of several domains important for hormone binding and transcription activation. Progesterone receptor ( PGR) is located in 11q22-23 and mediates the role of progesterone interacting with different transcriptional co-regulators. ESR1 and PGR have previously been implicated in migraine susceptibility. Here, we report the results of an association study of these genes in a migraine pedigree from the genetic isolate of Norfolk Island, a population descended from a small number of Isle of Man “Bounty Mutineer” and Tahitian founders.

Methods

A significant number of molecular markers in the ESR1 (143) and PGR (43) genes were evaluated in a sample of 285 related individuals (135 males; 150 females). A pedigree-based analysis in the GenABEL package was used to analyse the results.

Results and conclusions

A total of 10 markers in the ESR1 gene showed association with migraine ( p < 0.05) in the Norfolk Island population. No association was detected with PGR. Three haplotypes in ESR1 were found to be associated with migraine ( p = 0.004, 0.03, 0.005). Future genetic studies in larger populations and expression analysis are required to clarify the role of ESR1 in migraine susceptibility.

Emerging genomic biomarkers in migraine

Migraine is a debilitating neurovascular condition classified as either migraine with aura or migraine without aura. A significant genetic basis has been implicated in migraine and has probed the role of neurotransmitters, hormones and vascular genes in this disorder. The aim of this review is to highlight the recent genetic discoveries contributing to our understanding of the complex pathogenesis of migraine. The current review will discuss the role of neurotransmitter-related genes in migraine, including the recently identified TRESK and variants of the KCNN3 gene, as well as outlining studies investigating hormone receptor genes, such as ESR1 and PGR, and vascular-related genes, including the MTHFR and NOTCH 3 genes.

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.

Interaction among nitric oxide (NO)-related genes in migraine susceptibility

The pathogenic mechanisms involved in migraine are complex and not completely clarified. Because there is evidence for the involvement of nitric oxide (NO) in migraine pathophysiology, candidate gene approaches focusing on genes affecting the endothelial function have been studied including the genes encoding endothelial NO synthase (eNOS), inducible NO synthase (iNOS), and vascular endothelial growth factor (VEGF). However, investigations on gene-gene interactions are warranted to better elucidate the genetic basis of migraine. This study aimed at characterizing interactions among nine clinically relevant polymorphisms in eNOS (T(-786)C/rs2070744, the 27 bp VNTR in intron 4, the Glu298Asp/rs1799983, and two additional tagSNPs rs3918226 and rs743506), iNOS (C(-1026)A/rs2779249 and G2087A/rs2297518), and VEGF (C(-2578)A/rs699947 and G(-634)C/rs2010963) in migraine patients and control group. Genotypes were determined by real-time polymerase chain reaction using the Taqman(®) allele discrimination assays or PCR and fragment separation by electrophoresis in 99 healthy women without migraine (control group) and in 150 women with migraine divided into two groups: 107 with migraine without aura and 43 with aura. The multifactor dimensionality reduction method was used to detect and characterize gene-gene interactions. We found a significant interaction between eNOS rs743506 and iNOS 2087G/A polymorphisms in migraine patients compared to control group (P < 0.05), suggesting that this combination affect the susceptibility to migraine. Further studies are needed to determine the molecular mechanisms explaining this interaction.

Potential role of aromatase over estrogen receptor gene polymorphisms in migraine susceptibility: a case control study from North India

Background

The present study was undertaken to find out the role of estrogen pathway related gene polymorphisms in susceptibility to migraine in Northern Indian population. Aromatase, CYP19A1 (rs10046 and rs4646); estrogen receptors, ESR1 (rs2234693, rs1801132, rs2228480 and rs9340799) and ESR2 (rs1271572 and rs1256049) polymorphisms were selected for the present study.

Methodology/Principal Findings

The patients were recruited in two cohorts – primary (207) and replicative (127) along with 200 healthy controls and genotyped for various polymorphisms. Logistic regression analysis was applied for statistical analyses. The results were validated in the replicative cohort and pooled by meta analysis using Fisher's and Mantel-Haenszel test. Furthermore, Benjamini – Hochberg false discovery rate test was used to correct for multiple comparisons. CYP19A1 rs10046 and CYP19A1 rs4646 polymorphisms were found to confer risk and protective effect, respectively. Out of four ESR1 polymorphisms, only rs2234693 variant allele was significantly associated in migraine with aura. No significant associations were observed for ESR2 polymorphisms. Significant haplotypes were identified for CYP19A1 and ESR1 polymorphisms. Gene- gene interactions of genotypes as well as haplotypes were observed for CYP19A1- ESR1 showing both risk and protective combinations.

Conclusion

We strongly suggest CYP19A1 polymorphisms to be the major contributing factors in migraine susceptibility instead of genetic variants of estrogen receptors.

Family-based association study of chromosome 6p12.2-p21.1 migraine locus

BACKGROUND

One of the genome-wide linkage studies performed in migraine has yielded a significant linkage of migraine (with and without aura) with markers located at 6p12.2-21.1. This locus (named MIGR3) has not been replicated in the only genome-wide association scan study performed to date or in previous genome-wide linkage studies.

OBJECTIVE

Our objective had been to replicate the MIGR3 locus performing a family-based association study.

METHODS

A sample of 594 subjects belonging to 134 migraine families of diverse complexity underwent genotyping for the markers previously published as linked at 6p12.2-21.1 migraine locus. Family-based association test, under different models of inheritance, and also the model-free TDT analysis were performed.

RESULTS

The best result was obtained with the D6S1650 marker under the additive model (rank [S observed] = 265.0; permuted P = .0006), using family-based association test program (HBAT subprogram). Similar results were obtained with the model-free TDTPHASE algorithm (P < .0001, corrected). Nominal significant P values were obtained for D6S1630, D6S452, and D6S257. After correction for multiple testing with the stratified false-discovery rate, all markers showed significant association (P < .0001).

CONCLUSION

We corroborated that the MIGR3 locus at 6p12 is a genetic risk for migraine with and without aura.

Variants in the human potassium channel gene (KCNN3) are associated with migraine in a high risk genetic isolate

The calcium-activated potassium ion channel gene (KCNN3) is located in the vicinity of the familial hemiplegic migraine type 2 locus on chromosome 1q21.3. This gene is expressed in the central nervous system and plays a role in neural excitability. Previous association studies have provided some, although not conclusive, evidence for involvement of this gene in migraine susceptibility. To elucidate KCNN3 involvement in migraine, we performed gene-wide SNP genotyping in a high-risk genetic isolate from Norfolk Island, a population descended from a small number of eighteenth century Isle of Man ‘Bounty Mutineer’ and Tahitian founders. Phenotype information was available for 377 individuals who are related through the single, well-defined Norfolk pedigree (96 were affected: 64 MA, 32 MO). A total of 85 SNPs spanning the KCNN3 gene were genotyped in a sub-sample of 285 related individuals (76 affected), all core members of the extensive Norfolk Island ‘Bounty Mutineer’ genealogy. All genotyping was performed using the Illumina BeadArray platform. The analysis was performed using the statistical program SOLAR v4.0.6 assuming an additive model of allelic effect adjusted for the effects of age and sex. Haplotype analysis was undertaken using the program HAPLOVIEW v4.0. A total of four intronic SNPs in the KCNN3 gene displayed significant association (P < 0.05) with migraine. Two SNPs, rs73532286 and rs6426929, separated by approximately 0.1 kb, displayed complete LD (r² = 1.00, D′ = 1.00, D′ 95% CI = 0.96–1.00). In all cases, the minor allele led to a decrease in migraine risk (beta coefficient = 0.286–0.315), suggesting that common gene variants confer an increased risk of migraine in the Norfolk pedigree. This effect may be explained by founder effect in this genetic isolate. This study provides evidence for association of variants in the KCNN3 ion channel gene with migraine susceptibility in the Norfolk genetic isolate with the rarer allelic variants conferring a possible protective role. This the first comprehensive analysis of this potential candidate gene in migraine and also the first study that has utilised the unique Norfolk Island large pedigree isolate to implicate a specific migraine gene. Studies of additional variants in KCNN3 in the Norfolk pedigree are now required (e.g. polyglutamine variants) and further analyses in other population data sets are required to clarify the association of the KCNN3 gene and migraine risk in the general outbred population.

Genetics of menstrual migraine: the molecular evidence

Migraine is considered to be a multifactorial disorder in which genetic, environmental, and, in the case of menstrual and menstrually related migraine, hormonal events influence the phenotype. Certainly, the role of female sex hormones in migraine has been well established, yet the mechanism behind this well-known relationship remains unclear. This review focuses on the potential role of hormonally related genes in migraine, summarizes results of candidate gene studies to date, and discusses challenges and issues involved in interpreting hormone-related gene results. In light of the molecular evidence presented, we discuss future approaches for analysis with the view to elucidate the complex genetic architecture that underlies the disorder.

Meta-analysis of genome-wide association for migraine in six population-based European cohorts

Migraine is a common neurological disorder with a genetically complex background. This paper describes a meta-analysis of genome-wide association (GWA) studies on migraine, performed by the Dutch–Icelandic migraine genetics (DICE) consortium, which brings together six population-based European migraine cohorts with a total sample size of 10 980 individuals (2446 cases and 8534 controls). A total of 32 SNPs showed marginal evidence for association at a P-value<10⁻⁵. The best result was obtained for SNP rs9908234, which had a P-value of 8.00 × 10⁻⁸. This top SNP is located in the nerve growth factor receptor (NGFR) gene. However, this SNP did not replicate in three cohorts from the Netherlands and Australia. Of the other 31 SNPs, 18 SNPs were tested in two replication cohorts, but none replicated. In addition, we explored previously identified candidate genes in the meta-analysis data set. This revealed a modest gene-based significant association between migraine and the metadherin (MTDH) gene, previously identified in the first clinic-based GWA study (GWAS) for migraine (Bonferroni-corrected gene-based P-value=0.026). This finding is consistent with the involvement of the glutamate pathway in migraine. Additional research is necessary to further confirm the involvement of glutamate.

Genetic variability in estrogen disposition: Potential clinical implications for neuropsychiatric disorders

Variability in the physiological levels of neuroactive estrogens is widely believed to play a role in predisposition to several disorders of the central nervous system. Local biosynthesis of estrogens in the brain as well as their circulating serum levels are known to contribute to this pool of neuroactive steroids. It has been well accepted that estrogens modulate neuronal functions by affecting genesis, differentiation, excitability, and degeneration of nerve cells. These actions of estrogens appear to be more prominent in females with higher concentrations and marked variability of circulating serum levels occurring over a woman's lifetime. However, our knowledge regarding the variability of neuroactive steroid levels is very limited. Furthermore, several studies have recently reported differences in the synchronization of circulating and neuronal levels of estradiol. In the absence of reliable circulating steroid levels, knowledge of genetic variability in estrogen disposition may play a determining factor in predicting altered susceptibility or severity of neuropsychiatric disorders in women. Over the past decade, several genetic variants have been linked to both differential serum estrogen levels and predisposition to diverse types of neuropsychiatric disorders in women. Polymorphisms in genes encoding estrogen-metabolizing enzymes as well as estrogen receptors may account for this phenotypic variability. In this review, we attempt to show the contribution of genetics in determining estrogenicity in females with a particular emphasis on the central nervous system. This knowledge will further provide a driving force for unearthing the novel field of "Estrogen Pharmacogenomics." © 2010 Wiley-Liss, Inc.

Sex hormone receptor gene polymorphisms and migraine: a systematic review and meta-analysis

BACKGROUND

Data on the association between sex hormone receptor polymorphisms and migraine are conflicting.

METHODS

We performed a systematic review and meta-analysis on this topic searching for studies published until August 2009. For each study, we calculated odds ratios (ORs) and 95% confidence intervals (CIs) assuming additive, dominant, and recessive genetic models. We then calculated pooled ORs and 95% CIs.

RESULTS AND CONCLUSION

Among the seven genes targeted, four variants were investigated in multiple studies. Effect estimates from an additive model suggest that the ESR-1 594 G>A (pooled OR 1.37; 95% CI 1.02-1.83) and ESR-1 325 C>G (pooled OR 1.16; 95% CI 1.03-1.32) variants are associated with any migraine. This pattern does not differ between migraine with and without aura. In contrast, the ESR-1 Pvu II C>T and PGR PROGINS insert polymorphism do not appear to be associated with migraine. Results were driven by studies among Caucasians and may differ in other ethnic groups.

Molecular genetics of migraine

Migraine is an episodic neurovascular disorder that is clinically divided into two main subtypes that are based on the absence or presence of an aura: migraine without aura (MO) and migraine with aura (MA). Current molecular genetic insight into the pathophysiology of migraine predominantly comes from studies of a rare monogenic subtype of migraine with aura called familial hemiplegic migraine (FHM). Three FHM genes have been identified, which all encode ion transporters, suggesting that disturbances in ion and neurotransmitter balances in the brain are responsible for this migraine type, and possibly the common forms of migraine. Cellular and animal models expressing FHM mutations hint toward neuronal hyperexcitability as the likely underlying disease mechanism. Additional molecular insight into the pathophysiology of migraine may come from other monogenic syndromes (for instance cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, which is caused by NOTCH3 mutations), in which migraine is prominent. Investigating patients with common forms of migraine has had limited successes. Except for 5',10'-methylenetetrahydrolate reductase, an enzyme in folate metabolism, the large majority of reported genetic associations with candidate migraine genes have not been convincingly replicated. Genetic linkage studies using migraine subtypes as an end diagnosis did not yield gene variants thus far. Clinical heterogeneity in migraine diagnosis may have hampered the identification of such variants. Therefore, the recent introduction of more refined methods of phenotyping, such as latent-class analysis and trait component analysis, may be certainly helpful. Combining the new phenotyping methods with genome-wide association studies may be a successful strategy toward identification of migraine susceptibility genes. Likely the identification of reliable biomarkers for migraine diagnosing will make these efforts even more successful.