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

Dopamine and Migraine: Biology and Clinical Implications

In the last 30 years dopamine has been considered as playing a role in the pathogenesis of migraine. The literature indicates that migraineurs are hypersensitive to dopamine agonists with respect to some of the premonitory symptoms of migraine such as nausea and yawning. There are various nonspecific dopamine D2 receptor antagonists that show good clinical efficacy in migraine, and also a number of polymorphisms of dopaminergic genes related to migraine. Animal studies have also shown that dopamine receptors are present in the trigeminovascular system, the area believed to be involved in headache pain, and neuronal firing here is reduced by dopamine agonists. There appears to be little effect of dopamine on peripheral trigeminal afferents. We assess some of the limitations of the clinical studies with regard to the therapeutics, and those found in the studies that discovered differences in genetic polymorphisms in migraine, and consider the implications of this on a dopaminergic hypothesis of migraine.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Dopaminergic symptoms in migraine

Migraine pain is often preceded, accompanied and followed by dopaminergic symptoms (premonitory yawning and somnolence, accompanying nausea and vomiting, postdromal somnolence, euphoria and polyuria). After reviewing evidence from pharmacological, biochemical, genetic and animal experimental studies on the relationship between dopamine and migraine, and matching these data with patients' clinical features, we postulate that migraine attacks could be characterized by an ictal dopamine release in a subject with dopamine receptor hypersensitivity due to a chronic dopaminergic deficit synergistic to serotoninergic impairment. Our review suggests that when the attack begins, a low dopamine plasma concentration stimulates hypersensitive central presynaptic dopamine receptors thus causing prodromal symptoms such as yawning and somnolence. Increasing dopamine levels, though still insufficient to stop trigeminovascular activation, stimulate postsynaptic dopamine receptors thus inducing nausea, vomiting and hypotension. Finally, dopamine levels slowly return to baseline, giving rise to somnolence and fatigue, but, in some cases, continue to rise triggering postdromal symptoms such as euphoria and polyuria.

Recent progress in migraine pathophysiology: role of cortical spreading depression and magnetic resonance imaging

Migraine is characterised by debilitating pain, which affects the quality of life in affected patients in both the western and the eastern worlds. The purpose of this article is to give a detailed outline of the pathophysiology of migraine pain, which is one of the most confounding pathologies among pain disorders in clinical conditions. We critically evaluate the scientific basis of various theories concerning migraine pathophysiology, and draw insights from brain imaging approaches that have unraveled the prevalence of cortical spreading depression (CSD) in migraine. The findings supporting the role of CSD as a physiological substrate in clinical pain are discussed. We also give an exhaustive overview of brain imaging approaches that have been employed to solve the genesis of migraine pain, and its possible links to the brainstem, the neocortex, genetic endophenotypes, and pathogenetic factors (such as dopaminergic hypersensitivity). Furthermore, a roadmap is proposed to provide a better understanding of pain pathophysiology in migraine, to enable the development of strategies using leads from brain imaging studies for the identification of early biomarkers, efficient prognosis, and treatment planning, which eventually may help in alleviating some of the devastating impact of pain morbidity in patients afflicted with migraine.

Biomarkers associated with migraine and their potential role in migraine management

OBJECTIVE

The focus of this review is to review potential diagnostic and therapeutic biomarkers associated with migraine.

BACKGROUND

Migraine headache is a common disease that affects millions of individuals worldwide. Although well-accepted diagnostic criteria exist for migraine, it is still a complex disorder that remains both underdiagnosed and misdiagnosed. The causes of migraine are likely a mix of genetic, epigenetic, and environmental factors that, together with the individual's life history, translate into the observed clinical heterogeneity. Inherent clinical heterogeneity is an obstacle in developing more effective treatments. The lack of appropriate biomarkers is also an impediment to developing more effective therapeutic/preventive approaches. Ultimately, biomarkers may facilitate the goal of individualized medicine by enabling clinicians to more accurately diagnose and treat migraine and other types of headache.

METHODS

A comprehensive review was conducted of PubMed citations containing the key word "marker" OR "biomarker" combined with "migraine" OR "headache." Other key words included "serum," "saliva," "cerebrospinal fluid," "genes," "blood," and "inflammation." The only restriction was English-language publication. The abstracts of all articles meeting these criteria were reviewed, and full text was retrieved and examined for relevant references.

RESULTS

Data from human studies have begun to identify genetic mutations/polymorphisms and altered levels of specific proinflammatory and neuromodulatory molecules that strongly correlate with migraine as well as symptom severity. Results from a smaller number of studies have identified parameters, such as the neuropeptide calcitonin gene-related peptide (CGRP), which are significantly associated with response to specific treatments for acute migraine attacks and prophylaxis. Epigenetic mechanisms may also be involved in the development of migraine, and understanding environmentally induced genetic changes associated with this disease may eventually guide the development of therapies capable of reversing these pathophysiological changes in gene function.

CONCLUSIONS

The understanding of the etiology of migraine is incomplete. Although the identification and validation of biomarkers has greatly advanced diagnostic precision and measures of therapeutic efficacy in other diseases, there are no currently accepted biomarkers for chronic or episodic migraine. However, the continued investigation and identification of genetic, epigenetic, and molecular biomarkers is likely to facilitate the goal of individualizing medicine by enabling clinicians to more accurately diagnose and treat migraine and other headache disorders.

Identification of a novel ANKK1 and other dopaminergic (DRD2 and DBH) gene variants in migraine susceptibility

The dopaminergic system plays an important role in migraine and its clinical subtypes. Hypersensitization of dopamine receptor type 2 (DRD2) in migraine led to successful administration of receptor antagonists in antimigraine therapy. Ankyrin repeats and kinase domain containing 1 (ANKK1) gene in DRD2 loci is linked to comorbid neurological disorders. Dopamine beta hydroxylase (DBH) is responsible for maintaining dopamine-to-norepinephrine ratio implicated in migraine pathophysiology. Therefore, we aimed to look for association of functional variants in ANKK1 (rs1800497), DRD2 (rs6275 and rs1799732) and DBH (rs7239728 and rs1611115) genes with migraine susceptibility. The present study was carried out in two dependent cohorts (n primary = 208, n secondary = 127, n controls = 200). The results of the cohorts were pooled by meta-analysis using Fisher's and Mantel-Haenszel test. Benjamini-Hochberg false discovery rate test was used to correct for multiple comparisons. Computer algorithm-based TANGO, WALTZ and LIMBO predictions were used to evaluate the effect of missense polymorphism (rs1800497). For ANKK1 polymorphism, variant genotype and allele showed significant associations with migraine risk. A significant protective effect of variant DRD2 rs6275 polymorphism was noticed. DBH rs7239728 imparted significant risk at genotypic, allelic and carrier analyses. We identified a risk haplotype in DRD2 loci. Two genotype interactions between ANKK1rs1800497 and DBHrs72393728 polymorphisms showed significant risks. The variant gene product of ANKK1 rs1800497 was predicted with decreased aggregation of ANKK1 protein. In conclusion, we identified novel genetic variants, haplotype and gene interactions in dopaminergic pathway as potential risk factors for migraine susceptibility.

Increased dopamine is associated with the cGMP and homocysteine pathway in female migraineurs

BACKGROUND

The group of catecholamines, which include dopamine, adrenaline, and noradrenaline, are neurotransmitters which have been considered to play a role in the pathogenesis of migraine. However, the impact of catecholamines, especially dopamine on migraine as well as the exact mechanisms is not clear to date as previous studies have yielded in part conflicting results.

OBJECTIVE

This study aimed to produce a comprehensive examination of dopamine in migraineurs.

METHODS

Catecholamines and various parameters of the homocysteine, folate, and iron metabolism as well as cyclic guanosine monophosphate (cGMP) and inflammatory markers were determined in 135 subjects.

RESULTS

We found increased dopamine levels in the headache free period in female migraineurs but not in male patients. Increased dopamine is associated with a 3.30-fold higher risk for migraine in women. We found no significant effects of aura symptoms or menstrual cycle phases on dopamine levels. Dopamine is strongly correlated with cGMP and the homocysteine-folate pathway.

CONCLUSION

We show here that female migraineurs exhibit increased dopamine levels in the headache free period which are associated with a higher risk for migraine.

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.

Platelet Dopamine: D2 Receptor Binding in Patients with Migraine

Clinical, genetic and pharmacological evidences suggest an abnormality of the dopaminergic system in the pathogenesis of migraine. Direct evidence of an abnormal metabolism of dopamine in migraine, however, is lacking. Platelets are a useful model to understand brain dopaminergic mechanisms. The present study has been undertaken to study the status of platelet dopamine receptor binding by carrying out radioligand receptor binding assay. Binding of3H-spiperone to platelet membranes, known to label dopamine (DA)—D2 receptors, was conducted in 20 patients with migraine and an equal number of healthy controls. The equilibrium dissociation constant (Kd) in patients with migraine (1.71 ± 0.19 nM) was found to be significantly lower ( P < 0.001) as compared with controls (3.14 ± 0.33 nM). However, no significant change was observed in the maximal number of binding sites (Bmax) in patients with migraine. No relationship of Kd with type of migraine, presence of vomiting, family history, frequency of attack, duration of illness and menstrual migraine was observed. The findings of the present study provide support for the involvement of the dopaminergic system in migraine.

New genetic evidence for involvement of the dopamine system in migraine with aura

In order to systematically test the hypothesis that genetic variation in the dopamine system contributes to the susceptibility to migraine with aura (MA), we performed a comprehensive genetic association study of altogether ten genes from the dopaminergic system in a large German migraine with aura case-control sample. Based on the genotyping results of 53 variants across the ten genes in 270 MA cases and 272 controls, three genes-DBH, DRD2 and SLC6A3-were chosen to proceed to additional genotyping of 380 MA cases and 378 controls. Four of the 26 genotyped polymorphisms in these three genes displayed nominally significant allelic P-values in the sample of 650 MA patients and 650 controls. Three of these SNPs [rs2097629 in DBH (uncorrected allelic P value = 0.0012, OR = 0.77), rs7131056 in DRD2 (uncorrected allelic P value = 0.0018, OR = 1.28) and rs40184 in SLC6A3 (uncorrected allelic P value = 0.0082, OR = 0.81)] remained significant after gene-wide correction for multiple testing by permutation analysis. Further consideration of imputed genotype data from 2,937 British control individuals did not affirm the association with DRD2, but supported the associations with DBH and SLC6A3. Our data provide new evidence for an involvement of components of the dopaminergic system-in particular the dopamine-beta hydroxylase and dopamine transporter genes-to the pathogenesis of migraine with aura.

The primary headaches: genetics, epigenetics and a behavioural genetic model

The primary headaches, migraine with (MA) and without aura (MO) and cluster headache, all carry a substantial genetic liability. Familial hemiplegic migraine (FHM), an autosomal dominant mendelian disorder classified as a subtype of MA, is due to mutations in genes encoding neural channel subunits. MA/MO are considered multifactorial genetic disorders, and FHM has been proposed as a model for migraine aetiology. However, a review of the genetic studies suggests that the FHM genes are not involved in the typical migraines and that FHM should be considered as a syndromic migraine rather than a subtype of MA. Adopting the concept of syndromic migraine could be useful in understanding migraine pathogenesis. We hypothesise that epigenetic mechanisms play an important role in headache pathogenesis. A behavioural model is proposed, whereby the primary headaches are construed as behaviours, not symptoms, evolutionarily conserved for their adaptive value and engendered out of a genetic repertoire by a network of pattern generators present in the brain and signalling homeostatic imbalance. This behavioural model could be incorporated into migraine genetic research.

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.

A dopamine D4 receptor exon 3 VNTR allele protecting against migraine without aura

OBJECTIVE

As dopamine plays an important role in the pathophysiology of migraine and antimigraine drugs have an effect on the dopamine system, the objective of this study was to examine the dopamine D4 receptor gene for involvement in the cause of migraine.

METHODS

We tested a VNTR-polymorphism in the dopamine D4 receptor gene, the exon 3 VNTR, in a sample of 190 family trios each with a proband with childhood migraine by using transmission disequilibrium test tests.

RESULTS

We found a trend for transmission distortion of this marker in migraine, with the common seven-repeat allele of the VNTR transmitted 58 times and not transmitted 82 times (global likelihood ratio score (LRS) = 12.27, degress of freedom (DF) = 6, p = 0.06; for the 7-repeat allele: chi(2) = 5.1, p = 0.02). This effect came only from migraine without aura (145 trios), with the common 7-repeat allele transmitted 45 times and not transmitted 69 times (global LRS = 15.18; DF = 6, p = 0.019; for the 7-repeat allele: chi(2) = 6.4, p = 0.01; odds ratio, 0.47), whereas in migraine with aura (45 trios) there was no transmission distortion of the 7-repeat allele.

INTERPRETATION

We conclude that seven-repeat allele of the dopamine D4 receptor VNTR is a protective factor for migraine without aura. Because migraine is a common disorder, this protective effect may have contributed to the positive selection acting on the dopamine D4 receptor exon 3 VNTR seven-repeat allele in recent human history. We speculate that dopamine function in the lateral parabrachial nucleus is involved in migraine without 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.

Genetics of dopamine metabolism, dopamine-β-hydroxylase and migraine

Evaluation of: Fernandez F, Lea RA, Colson NJ, Bellis C, Quinlan S, Griffiths LR: Association between a 19 bp polymorphism at the dopamine β-hydroxylase (DBH) locus and migraine with aura. J. Neurol. Sci. 251, 118–123 (2006). Several association studies have been performed in migraine genetics, often with still unverified or controversial findings. Genes implicated in the metabolism of dopamine (DA) and norepinephrine (NE) have been analyzed. Dopamine-β-hydroxylase (DBH) effects the conversion of DA into NE, and its enzymatic activity has been found to be altered in migraineurs. In a study of 275 migraineurs versus 275 controls, a significant genetic association was found between a 19 base pair deletion polymorphism in DBH and migraine with aura (MA), particularly in males. Males homozygous for the DBH deletion polymorphism had 3.7-times the risk for MA. These findings implicate DBH in the genetics of MA and are consistent with low NE and increased DA activities in migraine.

Genetic biomarkers for migraine

Biomarkers are physical signs or laboratory measurements that occur in association with a pathological process and have putative diagnostic and/or prognostic utility. In migraine, clinical, radiological, and biochemical biomarkers might be helpful to improve diagnosis, get insight in pathophysiology, and facilitate treatment choices. Genetic biomarkers are defined as genetic variations (mutations or polymorphisms) that can predict disease susceptibility, disease outcome, or treatment response. As yet, only a few genetic biomarkers for migraine are available. Mutations in 3 different genes responsible for familial hemiplegic migraine, a monogenetic subtype of migraine with aura, and the MTHFR C677T polymorphism in common forms of migraine are clear examples. Many positive findings from linkage studies and association studies in common forms of migraine have not been replicated, and are therefore of less clinical use. In this review, we will discuss genetic biomarkers in migraine.