MTHFR T677 homozygosis influences the presence of aura in migraineurs

It has been suggested that folate metabolism could be involved in migraine pathogenesis. We analysed the 5',10'-methylenetetrahydrofolate reductase (MTHFR) genotypic distribution in a large migraine sample. We genotyped 230 migraine patients (152 migraine without aura (MO) and 78 migraine with aura (MA)) and 204 nonheadache controls. The incidence of TT homozygosis for migraine in general (12%), MO (9%) and MA (18%) did not significantly differ from that found in healthy controls (13%). Differences were significant when the frequency of TT homozygosis between MA and MO (P = 0.03, OR = 2.34, 95% CI = 1.04-5.26) was compared. There was a tendency for a higher frequency of the MTHFR T allele in the MA group (42%) as compared to MO (29%) and controls (36%). These differences were significant only in the case of MA vs. MO (P = 0.006, OR = 1.75, 95% CI = 1.15-2.65). These results could indicate that the MTHFR C677T polymorphism, causing mild hyperhomocystinaemia, might be a genetic risk factor for experiencing aura among migraineurs. Overall, however, there was no association between migraine and the C677T MTHFR polymorphism.     

Search for correlations between genotypes and electrophysiological patterns in migraine: the MTHFR C677T polymorphism and visual evoked potentials

Interictally, migraineurs have on average a reduction in habituation of pattern-reversal visual evoked potentials (PR-VEP) and in mitochondrial energy reserve. 5,10-Methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism and its C677T polymorphism may be more prevalent in migraine. The aim of this study was to search in migraineurs for a correlation between the MTHFR C677T polymorphism and the PR-VEP profile. PR-VEP were recorded in 52 genotyped migraine patients: 40 female, 24 without (MoA), 28 with aura (MA). Among them 21 had a normal genotype (CC), 18 were heterozygous (CT) and 13 homozygous (TT) for the MTHFR C677T polymorphism. Mean PR-VEP N1-P1 amplitude was significantly lower in CT compared with CC, and tended to be lower in TT with increasing age. The habituation deficit was significantly greater in CC compared with TT subjects. The correlation between the cortical preactivation level, as reflected by the VEP amplitude in the first block of averages, and habituation was stronger in CC than in CT or TT. The MTHFR C677T polymorphism could thus have an ambiguous role in migraine. On one hand, the better VEP habituation which is associated with its homozygosity, and possibly mediated by homocysteine derivatives increasing serotoninergic transmission, may protect the brain against overstimulation. On the other hand, MTHFR C677T homozygosity is linked to a reduction of grand average VEP amplitude with illness duration, which has been attributed to brain damage.     

The Relationship Between Homocysteine and Genes of Folate-Related Enzymes in Migraine Patients

(Headache 2010;50:99‐168) Background.— It has been suggested that homocysteine (Hcy) and the 5′‐10′‐methylenetetrahydrofolate reductase (MTHFR) C677T variant are implicated in the pathogenesis of migraine. Homocysteine has the potential to damage endothelium and accelerate atherosclerosis. Genetic factors such as the MTHFR C677T polymorphism, and other polymorphisms in folate‐related genes associated with high homocysteine levels, may contribute to increasing this vascular risk. Results.— We recruited 427 migraine patients (199 without aura [MO]; 228 with aura [MA]), and 310 controls in a neurologic clinic. Hcy levels and 6 polymorphisms corresponding to 6 folate‐related genes, including the MTHFR C677T variant, were determined in all migraine participants and in a subset of 155 controls. We found higher sex‐adjusted Hcy levels in MA (mean: 11.02 µM) than MO patients (9.86 µM; P = .005 for the difference). Hcy levels higher than 12.0 µM doubled the risk for MA (OR = 2.145; 95% confidence intervals [CI] = 1.3‐3.4; P = .001), and those higher than 15.0 µM incurred a 6‐fold increase (OR = 5.95; 95% CI = 2.1‐20.0, P < .001). The number of MTHFR 677T alleles was the best genetic predictor of Hcy levels (r² = 0.06; P = 6.2e‐6; corrected for genetic variants analyzed) and this effect remained significant after correction for other confounding factors. Using multi‐dimensionality reduction approaches, we observed significant epigenetic interaction among some of the folate‐related genetic variants to predict higher Hcy levels, and also among higher Hcy levels and folate‐related genetic variants to predict the end‐diagnosis of MA only among migraineurs. In controls, Hcy levels and the number of MTHFR 677T alleles were found to be intermediate between those observed in MA and MO patients. Conclusion.— Our results suggest that MA patients have higher Hcy levels. We also observed complex epigenetic interaction among folate‐related enzymes, sex, and Hcy levels predicting MA phenotype. Nevertheless, genetic factors explained only a minor proportion of the variance for both Hcy plasma levels and for predicting MA phenotype. Determination of MTHFR C677T polymorphisms and Hcy levels may be useful to identify patients with a high risk of suffering from MA.     

Association of von Willebrand factor activity with ACE I/D and MTHFR C677T polymorphisms in migraine

Angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms are linked to endothelial dysfunction and to cerebral white matter lesions. Objectives of this study were to determine if ACE and MTHFR gene polymorphisms are associated with von Willebrand factor (vWF) activity, an endothelial dysfunction marker, and with a distinct headache phenotype. We enrolled 64 women (18–50 years old) with International Classification of Headache Disorders, 2nd edn migraine without aura (MoA) and 61 with aura (MA). Genotypic frequencies: ACE DD 35%, ID 42%, II 23%, and MTHFR TT 17%, CT 40%, CC 43%. Those with ACE DD genotype had higher levels of vWF activity (152%) compared with ID and II genotypes. Levels were highest (179%) with combined ACE DD and MTHFR TT genotypes. ACE DD was associated with higher headache frequency, and MTHFR TT was associated with MA. In migraine, vWF activity may be a marker of endothelial-mediated genetic risk for ischaemic conditions.     

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.     

Testing of variants of the MTHFR and ESR1 genes in 1798 Finnish individuals fails to confirm the association with migraine with aura

Among the few independently replicated genetic associations in migraine are polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) and oestrogen receptor (ESR1) genes. We studied the contribution of these genes to migraine susceptibility by genotyping six MTHFR and 26 ESR1 polymorphisms in 898 unrelated migraine with aura (MA) patients and in 900 unrelated healthy controls. There were no differences in the genotype distributions of the previously migraine-associated SNPs C677T (MTHFR) and G2014A (ESR1) between cases and controls (P-values 0.83 and 0.55, respectively). Thus, we were not able to replicate the previous findings, although our study had considerable power. However, five of the ESR1 SNPs (rs6557170, rs2347867, rs6557171, rs4870062 and rs1801132) that were in strong linkage disequilibrium were nominally associated with MA (uncorrected P-values 0.007-0.034). These results did not, however, remain significant after taking multiple testing into account. Thus it seems unlikely that the studied genes are involved in migraine susceptibility, at least in this sample.     

Contingent negative variation during migraine attack and interval: evidence for normalization of slow cortical potentials during the attack

The contingent negative variation (CNV) amplitudes of 16 subjects with migraine without aura were studied during pain-free intervals and during attacks and the results were compared with those of 22 healthy subjects. In 32 trials the CNV amplitudes were calculated for (a) "total interval", (b) "early CNV component", (c) "late CNV component", and (d) habituation. There was a significantly higher total CNV amplitude in migraine subjects during pain-free intervals compared to that of the healthy subjects and migraine patients during an attack. Healthy subjects as well as subjects studied during the attack showed a significant habituation whereas migraine subjects studied during pain-free intervals did not. This suggests that the higher CNV amplitude in migraine patients studied between pain-free attacks may be due in part to impaired habituation.     

Sporadic hemiplegic migraine is an aetiologically heterogeneous disorder

In order to better understand sporadic hemiplegic migraine (SHM) and particularly its relation to familial hemiplegic migraine (FHM), migraine without aura (MO) and typical migraine with aura (typical MA), we investigated the occurrence of MO and typical MA among probands with SHM and their first-degree relatives. The pattern of familial aggregation of MO and typical MA was assessed by population relative risk calculations. A total of 105 SHM probands and 483 first-degree relatives were identified in the Danish population. Compared with the general population, SHM probands had no increased risk of MO, but a highly increased risk of typical MA. First-degree relatives of all SHM probands had an increased risk of both MO and typical MA, whereas first-degree relatives of probands with exclusively SHM had no increased risk of MO but an increased risk of typical MA. Our data suggest that SHM is a genetically heterogeneous disorder.     

Median nerve somatosensory evoked potentials in migraine.

Eur J Neurol. 2002;9:227-232.
In visual evoked potential studies, habituation during stimulus repetition with the same stimulus at a constant intensity has been found to be abnormal in migraineurs between attacks. The purpose of this study was to investigate habituation of somatosensory evoked potentials (SEPs) and the effects of migraine on them. Eighty-five subjects were included in the study: 30 healthy volunteers (HVs) and 55 migraineurs [30 with migraine without aura (MO), 25 with migraine with aura (MA)]. During continuous stimulation at 3 Hz, four blocks of 100 responses were sequentially averaged of Erb's point (N9), cervical (N13), and cortical (N20) median nerve SEPs. Mean amplitude changes in the second, third and fourth blocks are expressed as percentages of the first block. There was habituation to N13 and N20 in the second, third and fourth blocks in HVs. In the migraine groups, there was no habituation; on the contrary, potentiation was found. This potentiation was statistically significant only in the second blocks for N13 (MO P   =  0.007, MA P   =  0.01 versus HVs). However, in both migraineur groups, the rate of N20 potentiations was statistically significant versus that in HVs for all blocks (all P < 0.05). It is concluded that whilst physiological habituation occurs in HVs for cervical and cortical SEPs, in migraine patients there is an interictal deficit of habituation of this sensory modality.
Comment: This interesting study confirms the lack of habituation to repetitive stimuli reported in migraineurs between attacks and extends this finding to somatosensory evoked potentials using median nerve stimulation. One might speculate that migraineurs lack a protective mechanism which modulates both cervical and cortical sensory inputs. DSM     

Association between migraine, lifestyle and socioeconomic factors: a population-based cross-sectional study

To investigate whether sex-specific associations exist between migraine, lifestyle or socioeconomic factors. We distinguished between the subtypes migraine with aura (MA) and migraine without aura (MO). In 2002, a questionnaire containing validated questions to diagnose migraine and questions on lifestyle and socioeconomic factors was sent to 46,418 twin individuals residing in Denmark. 31,865 twin individuals aged 20-71 were included. The twins are representative of the Danish population with regard to migraine and other somatic diseases and were used as such in the present study. An increased risk of migraine was significantly associated with lower level of schooling and education, retirement, unemployment, and smoking. A decreased risk of migraine was significantly associated with heavy physical exercise and intake of alcohol. Direct comparison between the subtypes showed a decreased risk of MA compared to MO in subjects with low education or weekly intake of alcohol. The risk of MA was increased compared to MO in unemployed or retired subjects. Direct comparison between sexes showed a decreased risk of migraine for men compared to women in subjects who were low educated, unemployed or studying. The risk was increased for men compared to women in subjects with heavy physical exercise, intake of alcohol, and body mass index >25. Migraine was associated with several lifestyle and socioeconomic factors. Most associations such as low education and employment status were probably due to the negative effects of having migraine while others such as smoking were risk factors for migraine.     

Contingent negative variation in patients with chronic daily headache

The aim of this study was the investigation of amplitude and habituation of contingent negative variation (CNV) in migraine and chronic daily headache (CDH) patients in order to describe possible neurophysiological features responsible for the clinical transformation and worsening of the headache. Fifteen females suffering from migraine without aura and 15 females diagnosed with CDH evolved from migraine without aura with interparoxysmal chronic tension-type headache (transformed migraine), underwent CNV recording. Fifteen healthy females matched for age served as controls. CNV was obtained from C3 and C4 using the standard reaction time paradigm and 3 sec ISI. The amplitudes and habituation of total CNV, early and late components, and of post-imperative negative variation (PINV) were calculated. The migraine patients were characterized by significantly more pronounced negativity of the early component and total CNV, compared to CDH sufferers and controls. CDH patients demonstrated significantly reduced negativity of the late component and pronounced PINV compared to the other groups. The early component of CNV did not habituate in migraine or CDH patients. However, the impaired habituation in CDH was related to significantly lower amplitudes. These results support the diagnostic and scientific value of habituation in migraine research and therapy. Late components of CNV and PINV can be considered as predictive variables for transformation of migraine. The results are discussed in terms of the relationship between late CNV, PINV, environment control abilities and susceptibility for development of depression.     

Metabolic and genetic risk factors for migraine in children

Migraine can induce ischaemic stroke, and is considered an independent risk factor for stroke in the young. To date, the nature of the link between migraine and stroke is essentially unknown. Forty-five children were studied. Homocysteine levels (fasting and post methionine load), vitamin B12 and plasma folate levels, factor V Leiden, factor II G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C mutations were examined. Compared with controls, patients with migraine had higher levels of post-methionine load homocysteine values (19.5 +/- 4.9 vs. 16.9 +/- 1.9; P = 0.025) and significantly lower folate levels (5.8 +/- 2.6 vs. 7.5 +/- 2.1; P = 0.002). We found a trend toward an increased risk of migraine in subjects carrying a homozygous mutant genotype for MTHFR C677T and MTHFR A1298C polymorphisms. Genetic prothrombotic conditions do not seem to be related to migraine in the young, whereas the biochemical differences between migrainous patients and controls are an appealing topic for further investigation.     

Contingent negative variation in subjects at risk for migraine without aura.

Migraine is a complex disease with a significant genetic background. One possible strategy to investigate the genetics of migraine is the evaluation of functional vulnerability markers or biological elementary endophenotypes in individuals with the greatest probability of developing the disorder (high-risk design). In this study the contingent negative variation (CNV) was recorded in 35 high-risk subjects with a positive family history of migraine without aura (FHP), 35 low-risk individuals without a positive family history (FHN), and 35 migraineurs (migraine without aura). FHP subjects and migraine patients differed significantly from FHN individuals with regard to amplitude and habituation slope of the early CNV component (initial CNV or iCNV). FHP participants demonstrated the same iCNV abnormalities and distribution among iCNV characteristics as migraineurs. The amplitude of the iCNV correlated significantly with the relative number of subjects suffering from migraine among first- and second-degree relatives. The higher the density of affected individuals in the family, the more pronounced were the CNV abnormalities in relatives. This study provides evidence that the familial factor contributes to the abnormal amplitude, and to a lesser degree, habituation of the iCNV, and that the iCNV may be used as a functional-genetic vulnerability marker in further research of migraine genetics.     

Cortical hyperexcitability is cortical under-inhibition: evidence from a novel functional test of migraine patients

Recent studies of the visual cortex in patients with migraine have generally concluded that migraine (particularly migraine with aura) is associated with a state of functional cortical hyperexcitability. The mechanisms giving rise to this hyperexcitability have hitherto been unclear. This paper reports two studies that used a novel investigative technique, derived from basic research in vision science, to examine specific deficits of inhibitory processing in primary visual cortex. The technique is termed the metacontrast test, and it examines visual masking under highly specified conditions. In Study 1, 12 migraine with aura patients (MA), 12 age-matched migraine without aura patients (MO) and 12 age- and sex-matched headache-free control subjects (C) were compared using the metacontrast test. MA patients were significantly less susceptible to visual masking in the metacontrast test than both MO and C groups: this result is highly consistent with a deficit in cortical inhibitory processing in MA patients. Study 2 examined MA patients taking a variety of migraine prophylactics, again using the metacontrast test. Test results normalized in those MA patients taking sodium valproate, but not in those taking other prophylactics. Sodium valproate is a GABA-A agonist that is known to cross the blood-brain barrier: GABA-ergic networks act as the primary inhibitory mechanism in visual cortex. Taken together, the results of these studies argue that cortical hyperexcitability, at least in MA patients, is likely to be a result of deficient intracortical inhibitory processes.     

Migraine without aura and migraine with aura are inherited disorders

The familial occurrence and mode of inheritance were analysed in families with migraine without aura (MO) and migraine with aura (MA). The probands were found among 4000 persons from the general population. All persons with MA were included as probands, and an equivalent number of probands with MO was selected as a random sample among those with MO. Spouses and first-degree relatives were blindly interviewed. All interviews were performed by one neurological research fellow. The distinct familial patterns indicate that MO and MA have a different aetiology. Compared with the general population, the first-degree relatives of probands with MO had a 1.9-fold increased risk of MO while spouses had a 1.5-fold increased risk of MO, indicating that both genetic and environmental factors are important in MO. The first-degree relatives of probands with MA had a four-fold increased risk of MA while spouses had no increased risk of MA, indicating that MA is determined largely by genetic factors. The complex segregation analysis indicate that both MO and MA have multifactorial inheritance without generational difference.     

Migraine with aura and migraine without aura: an epidemiological study

In a cross-sectional study of headache disorders in a representative general population of 1,000 persons the epidemiology of migraine with aura (MA) and migraine without aura (MO) was analysed in relation to sex and age distribution, symptomatology and precipitants. The headache disorders were classified on the basis of a clinical interview as well as a physical and a neurological examination using the operational diagnostic criteria of the International Headache Society (IHS). Lifetime prevalence of MA was 5%, male:female ratio 1:2. Lifetime prevalence of MO was 8%, M:F ratio 1:7. Women, but not men, were significantly more likely to have MO than MA. Neither MA nor MO showed correlation to age in the studied age interval (25-64 years). Premonitory symptoms occurred in 16% of subjects with MA and in 12% with MO. One or more precipitating factor was present in 61% with MA and in 90% with MO. In both MA and MO the most conspicuous precipitating factor was stress and mental tension. Visual disturbances were the most common aura phenomenon occurring in 90% of subjects with MA. Aura symptoms of sensory, motor or speech disturbances rarely occurred without coexisting visual disturbances. The pain phase of MA fulfilled the criteria for MO of the IHS. Headache was, however, less severe and shorter lasting in MA than in MO. Onset at menarche, menstrual precipitation, menstrual problems, influence of pregnancy and use of oral contraceptives all showed some relationship with the presence of MO and less with MA. The present findings suggest that MA and MO share the pain phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex-hormone-related events in migrainous females. A clinical comparative study between migraine with aura and migraine without aura

In this study, the relationship between hormonal-related events and migraine with aura (MA) and without aura (MO) was investigated. Subjects included 268 women suffering from MA (88) and MO (180). Data were collected on the relationship between sex-hormone-related events and migraine. Migraine during menses was observed in a significantly higher percentage of MO than MA patients ( p < 0.03). Menstrual migraine was significantly more common in MO than in MA patients ( p < 0.01). Migraine began during pregnancy in a significantly higher percentage of MA than of MO patients ( p < 0.01). No significant difference was observed between the two groups of patients regarding the onset of migraine at menarche, after menopause, in the postpartum period or during the early cycles of oral contraceptives. Also, both groups of patients showed a similar migraine course during pregnancy, oral contraceptive use and menopause. Eight patients with coexisting migraine with aura and migraine without aura attacks reported the appearance of the aura symptom for the first time in the early cycles of oral contraceptive intake. These findings suggest that gonadal hormone fluctuation may influence both types of migraine.     

Headache in juvenile myoclonic epilepsy

The objective of this study was to assess the prevalence of and risk factors for primary headaches in juvenile myoclonic epilepsy (JME). Headache was classified in 75 patients with JME using a questionnaire, and its prevalence was correlated with the literature on the general population and clinical data. Headache was present in 47 patients. Thirty-one had migraine [20 migraine without aura (MO), 11 migraine with aura (MA)]. Fourteen patients with migraine had tension-type headache (TTH) in addition. Sixteen had only TTH. Comparison with the general population revealed a significantly higher prevalence of migraine (RR 4.4), MO (3.6), MA (7.3) and TTH (3.4) in JME. Risk factors for migraine and MO were female gender and for MA family history of migraine in first-degree relatives. Migraine and MA were associated with fairly controlled generalized tonic clonic seizures, MO with absences. Together with its strong genetic background, JME appears to be an attractive homogenous subtype of epilepsy for genetic research on migraine.     

Contingent negative variation: methods and potential interest in headache

Contingent negative variation (CNV) is an event-related slow cerebral potential which has been found abnormal in migraine. Its methodology is described. Contrary to other neurophysiological techniques, CNV needs special equipment and expertise. On average, CNV amplitude is increased and its habituation is lacking in migraine without aura between attacks, but not in migraine with aura. The sensitivity of CNV as a diagnostic tool is low, but its specificity is high. CNV amplitude normalizes after treatment with beta-blockers. The CNV abnormalities in migraine might be due to hyperreactivity of central catecholaminergic pathways.     

Migraine with aura and reproductive life events: a case control study

The course of migraine without aura (MO) is greatly influenced by the events of female reproductive life. Much less is known about migraine with aura (MA). The aim of this study was to evaluate the relationship between MA and the milestones of reproductive life. A retrospective case control study was carried out on 100 women affected by migraine with typical aura (cases) and 200 age-matched women with MO (controls). Premenstrual syndrome was found to be much more common among the patients with MA (odds ratio (OR) 6.0; confidence interval (CI) 3.1-11.6). Menstrually triggered migraine was more frequently encountered among MO than among MA patients (MA 15.0%; MO 53.5%; OR 0.1; CI 0.1-0.3). In both forms of migraine, pregnancy had a favourable effect; however, a lower percentage of MA (43.6%) than MO patients (76.8%; OR 0.2; CI 0.1-0.5) showed improvement or remission. The use of oral contraceptives worsened migraine in MA more frequently than in MO patients (MA 56.4%; MO 25.3%; OR 3.8; CI 1.6-9.3). The course of MA seems to be influenced by female reproductive life events, but in a different way with respect to MO.