Association of MTHFR gene polymorphisms with migraine in North Indian population

Current Update on Categorization of Migraine Subtypes on the Basis of Genetic Variation: a Systematic Review

Migraine is a complex neurovascular disorder that is characterized by severe behavioral, sensory, visual, and/or auditory symptoms. It has been labeled as one of the ten most disabling medical illnesses in the world by the World Health Organization (Aagaard et al Sci Transl Med 6(237):237ra65, 2014). According to a recent report by the American Migraine Foundation (Shoulson et al Ann Neurol 25(3):252-9, 1989), around 148 million people in the world currently suffer from migraine. On the basis of presence of aura, migraine is classified into two major subtypes: migraine with aura (Aagaard et al Sci Transl Med 6(237):237ra65, 2014) and migraine without aura. (Aagaard K et al Sci Transl Med 6(237):237ra65, 2014) Many complex genetic mechanisms have been proposed in the pathophysiology of migraine but specific pathways associated with the different subtypes of migraine have not yet been explored. Various approaches including candidate gene association studies (CGAS) and genome-wide association studies (Fan et al Headache: J Head Face Pain 54(4):709-715, 2014). have identified the genetic markers associated with migraine and its subtypes. Several single nucleotide polymorphisms (Kaur et al Egyp J Neurol, Psychiatry Neurosurg 55(1):1-7, 2019) within genes involved in ion homeostasis, solute transport, synaptic transmission, cortical excitability, and vascular function have been associated with the disorder. Currently, the diagnosis of migraine is majorly behavioral with no focus on the genetic markers and thereby the therapeutic intervention specific to subtypes. Therefore, there is a need to explore genetic variants significantly associated with MA and MO as susceptibility markers in the diagnosis and targets for therapeutic interventions in the specific subtypes of migraine. Although the proper characterization of pathways based on different subtypes is yet to be studied, this review aims to make a first attempt to compile the information available on various genetic variants and the molecular mechanisms involved with the development of MA and MO. An attempt has also been made to suggest novel candidate genes based on their function to be explored by future research.

A Comprehensive Investigation into the Association Between Mthfr C677t, A1298c, and Ace I/D Variants and Risk of Migraine: an Updated Meta-Analysis of Genetic Association Studies with Trial Sequential Analysis and Meta-Regression

Many homeostatic genes are thought to play a role in the susceptibility to migraine, making it a highly complex neurovascular disease. In this meta-analysis, our primary objective was to evaluate whether or not MTHFR variants (such as C677T and A1289C) and ACE I/D were associated with an increased risk of migraine. Using a PRISMA-based systematic literature-review guideline, internet sources such as PubMed and Google Scholar were searched to identify the genes of interest and migraine risk. To pool the data, odds ratios with 95% confidence intervals were calculated utilizing different genetic models. Cochran's Q Test and I2 statistics were used to access heterogeneity, while Begg's and Egger's tests were used to identify publication bias. All tests were two-sided, and a p-value of < 0.05 was regarded as statistically significant. The present meta-analysis observed that the C677T variant is significantly associated with the increased risk of migraine (allele model: OR:1.19, CI [1.07-1.33], I2 = 78%) and its clinical subtype i.e., MA (allele model: OR: 1.26, CI [1.09-1.45], I2 = 80%) in the overall population. Concerning the ACE- I/D, it significantly increased the risk of overall migraine and both clinical subtypes after utilizing the dominant genetic models (OR: 1.14, CI [1.01-1.29], I2% = 32). Concerning the MTHFR A1289C, only the codominant model (HR vs HT) and recessive model significantly increased the risk of overall migraine. Therefore, the findings of the present meta-analysis showed that MTHFR-C677T is an important risk factor for migraine and its clinical subtype.

Comprehensive analysis of genes associated with migraine in the Indian population: a meta-analysis of genetic association studies with trial sequential analysis

Migraine is a complex disorder with multigenic inheritance and is characterized by the cardinal symptom of unilateral headache. Many genes are responsible for increasing the susceptibility of disease within different populations. Therefore, our primary aim in this review was to catalog the many genes that have been studied in India and after collecting the necessary information, we calculated a more precise risk relationship between an identified variation and migraine. The gene and its associated risk variant were discovered in the Indian population using a PRISMA-based systematic literature review guideline from online databases such as PubMed & Google Scholar. We constructed pooled odds ratios with 95% confidence intervals using multiple genetic models. Also, we looked for heterogeneity using Cochran's Q Test and the I2 statistic. Publication bias was analyzed using Begg's and Egger's tests. A p-value less than 0.05 was judged to be statistically significant for all tests. After a critical analysis, a total of 24 studies explored about 21 genes with 31 variants out of which only nine genes have been studied more than two times in the Indian population and thus were found eligible for the meta-analysis. It has been found, that the ACE-DD variant (allele model: OR: 1.37 [1.11-1.69], I2 = 0%/ fixed model), ESR1-PvuII (allele model: OR: 1.47 [1.24-1.74], I2 = 0%/ fixed model) significantly increases the risk of migraine in Indian population. Also, a protective role of the LRP1-rs11172113variant was observed for both migraine and its clinical subtype i.e., MA (allelic model: OR of 0.65 [0.50-0.83] I2 = 44% and allele: OR: 0.54 [0.37-0.78], I2 = 52%) respectively. Overall, the results of this meta-analysis indicated that the ACE-DD variant and the ESR1-PvuII were associated with an increased risk of migraine in the Indian community, while the LRP1-rs11172113 variant was associated with protection from migraine in this population.

Migraine and thyroid dysfunction: Co-occurrence, shared genes and biological mechanisms

BACKGROUND AND PURPOSE

Migraine and thyroid dysfunction, particularly hypothyroidism, are common medical conditions and are known to have high heritability. Thyroid function measures, thyroid stimulating hormone (TSH) and free thyroxine (fT4), are also known to be genetically influenced. Although observational epidemiological studies report an increased co-occurrence of migraine and thyroid dysfunction, a clear and combined interpretation of the findings is currently lacking. A narrative review is provided of the epidemiological and genetic association evidence linking migraine, hypothyroidism, hyperthyroidism and thyroid hormones TSH and fT4.

METHODS

An extensive literature search was conducted in the PubMed database for epidemiological, candidate gene and genome-wide association studies using the terms migraine, headache, thyroid hormones, TSH, fT4, thyroid function, hypothyroidism and hyperthyroidism.

RESULTS

Epidemiological studies suggest a bidirectional relationship between migraine and thyroid dysfunction. However, the nature of the relationship remains unclear, with some studies suggesting migraine increases the risk for thyroid dysfunction whilst other studies suggest the reverse. Early candidate gene studies have provided nominal evidence for MTHFR and APOE, whilst more recently genome-wide association studies have provided robust evidence for THADA and ITPK1 being associated with both migraine and thyroid dysfunction.

CONCLUSIONS

These genetic associations improve our understanding of the genetic relationship between migraine and thyroid dysfunction, provide an opportunity to develop biomarkers to identify migraine patients most likely to benefit from thyroid hormone therapy, and indicate that further cross-trait genetic studies have excellent potential to provide biological insight into their relationship and inform clinical interventions.

Genetic overlap between temporomandibular disorders and primary headaches: A systematic review

Primary headache disorders (PHD), specifically migraine, are strongly associated with temporomandibular disorders (TMD), sharing some patterns of orofacial pain. Both disorders have significant genetic contributions already studied. PRISMA guidelines were followed to conduct this systematic review, which comprehensively summarize and discuss the genetic overlap between TMD and PHD to aid future research in potential therapy targets. This review included eight original articles published between 2015 and 2020, written in English and related to either TMD and/or PHD. The genes simultaneously assessed in PHD and TMD studies were COMT, MTHFR, and ESR1. COMT was proved to play a critical role in TMD pathogenesis, as all studies have concluded about its impact on the occurrence of the disease, although no association with PHD was found. No proof on the impact of MTHFR gene regulation on either TMD or PHD was found. The most robust results are concerning the ESR1 gene, which is present in the genetic profile of both clinical conditions. This novel systematic review highlights not only the need for a clear understanding of the role of ESR1 and COMT genes in pain pathogenesis, but it also evaluates their potential as a promising therapeutic target to treat both pathologies.

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.

A Comprehensive Review on the Role of Genetic Factors in the Pathogenesis of Migraine

Migraine is a common neurovascular condition. This disorder has a complex genetic background. Several single-nucleotide polymorphisms (SNPs) or mutations within genes regulating glutamatergic neurotransmission, cortical excitability, ion channels, and solute carriers have been associated with polygenic and monogenic forms of migraine. SNPs within ACE, DBH, TRPM8, COMT, GABRQ, CALCA, TRPV1, and other genes have been reported to affect the risk of migraine or the associated clinical parameters. The distribution of some HLA alleles within the HLA-DRB1, HLA-DR2, HLA-B, and HLA-C regions have also been found to differ between migraineurs and healthy subjects. In addition, certain mitochondrial DNA changes and polymorphisms in this region have been shown to increase the risk of migraine. A few functional studies have investigated the molecular mechanisms contributing to these genetic factors in the development of migraine. Here we review studies evaluating the role of genetic polymorphisms and mRNA/miRNA dysregulation in migraine.

Could rs4379368 be a genetic marker for North Indian migraine patients with aura?: Preliminary evidence by a replication study

BACKGROUND

Genome wide association studies (GWAS) have already found different migraine single nucleotide polymorphisms (SNPs). To further check if these variants differ by ethnicity, three single nucleotide polymorphisms (SNPs) (rs4379368, rs10504861and rs11172113) were genotyped here to find association with migraine susceptibility from North Indian population.

METHODS AND RESULTS

A case control study in 200 subjects was done by polymerase chain reaction and restriction-fragment-length polymorphism (PCR-RFLP) analysis. Univariate analysis was performed to check the association of different genotypic and allelic frequencies of these variants with migraine and its subtypes. We could not find any statistically relevant differences among frequencies at various levels of these selected SNPs between patients and healthy controls in this study (p > 0.05). However on subgroup analysis for rs4379368 SNP, the CT genotype was higher in migraine with aura (MA) (69.6%) than migraine without aura (MO) (51.9%) or control (42%) (p < 0.05). But this relation was not significant at allelic level. For other two SNPs, statistically significant differences were not observed in any of the two migraine subgroups.

CONCLUSIONS

This study was able to associate the role of rs4379368 SNP with migraine susceptibility and suggested that genotype CT in rs4379368 SNP could be a possible genetic marker for MA. More studies with larger sample size are needed to strengthen our results.

rs2651899 variant is associated with risk for migraine without aura from North Indian population

Recently a GWAS study had identified 38 genomic variants commonly found in humans that influence migraine risk. For further replicate these findings, we selected two SNPs; rs2651899 on chromosome 1p36.32 in PRDM16 gene and rs10166942 on chromosome 2q37.1 close to TRPM8 gene for their associations with migraine in the North Indian population as much work has not been done on these variants before from this population. In this case-control association study, 300 unrelated subjects, including 150 migraineurs (43 migraine with aura and 107 migraine without aura) and 150 healthy controls were selected to collect genomic DNA. Polymerase chain reaction and restriction-fragment-length polymorphism methods were performed for genotyping of these variants. Univariate and multivariate analyses were done to find the association of different genotypes and alleles of these SNPs with migraine and its subgroups. We found a statistically significant difference in migraineurs with control for PRDM16 rs2651899 polymorphism at genotypic (p < 0.05), allelic (p = 0.022; OR 1.462; 95% CI 1.058-2.022) and for dominant model (p = 0.011; OR 1.957; 95% CI 1.169-3.276). A similar trend was observed both on subgroup and gender analysis in migraine without aura (MO) and females respectively for rs2651899 variant. For the other SNP (rs10166942), statistically non-significant differences were reported in the allelic/genotypic frequencies between migraineurs and controls as p > 0.05. However, on subgroup analysis we found statistically significant differences at genotypic (p < 0.05) and dominant models in migraine with aura (MA) and in males with that of entire controls. But no significant association was found at allelic level in both subgroup and gender analysis for rs10166942. This research study showed that rs2651899 is a potential genetic marker for migraine susceptibility in MO and female subgroup at both genotypic and allelic level in the North Indian population and found that rs10166942 variant may be a potential marker for MA and male subgroup. Further work with large sample size is required for these SNPs to understand their functional mechanisms and to strengthen our results.

Methylenetetrahydrofolate reductase polymorphism (MTHFR C677T) and headache in children: a retrospective study from a tertiary level outpatient service

Background

In adult studies the MTHFR C677T polymorphism has been associated with an increased risk of migraine, but little research has been done in this area in children.

Methods

A retrospective study of children referred with headache to a tertiary level Paediatric Neurology Service between 2008 and 2012. This study included only patients who had been genotyped for the MTHFR C677T polymorphism. An evaluation of homocysteine serum levels was necessary to exclude other types of migraine.

Conclusion

Compared with the wild-type genotype, the T/T genotype was associated with an increased risk of any type of migraine, though the statistical significance was greatest in migraine with aura. The homocysteine serum levels were significantly higher in migraine with aura compared to migraine without aura. In a pediatric population MTHFR T/T homozygosity influences susceptibility to migraine.