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

Pharmacogenetic considerations for migraine therapies

INTRODUCTION

Migraine is a common neurological disorder with a complex pathophysiology. It has been estimated that incidence between adults of current headache disorder is about 50%. Different studies show that this condition has an important and complex genetic component in response to drug therapy. Areas covered: This review shows and summarizes the importance of the polymorphisms associated with the major antimigraine drug metabolizing enzymes. The research of bibliographic databases has involved only published peer-reviewed articles from indexed journals. Expert opinion: Pharmacogenetics is based on the identification of polymorphism and promises personalized therapy with efficacy and reduction of adverse events. The association between genotype and an altered metabolizer status could guide clinical decision to evade concomitant treatments and adverse events. The introduction of routine genetic testing could help to choose the efficacy drug on the individual and genetic profile.

Association of endothelial nitric oxide synthase gene polymorphisms (894G/T, -786T/C, G10T) and clinical findings in patients with migraine

Migraine is a common neurological disorder characterized by recurrent attacks, unilateral head pain, and related symptoms. The aim of this study was to investigate three endothelial nitric oxide synthase (eNOS) polymorphisms in 176 patients with migraine and 123 healthy individuals. Clinical and biochemical parameters were investigated. Genetic analysis was performed using the polymerase chain reaction-restriction fragment length polymorphism method. The differences between migraine cases and the control group were significant for two polymorphisms (-786T/C and 894G/T) (p = 0.000). Homocysteine and body mass index (BMI) were significantly higher in the migraine group than in the control group (p = 0.001 and p = 0.000). The relation between -786T/C genotype and BMI and allodynia was significant. TC heterozygotes and CC homozygotes were significantly higher in the migraine group than in the control group (OR 2.843 and 95 % CI 1.681-4.808 and OR 3.729 and 95 % CI 1.784-7.792, respectively). The 894G/T genotype was correlated with BMI, pain intensity, age at the onset of migraine, nausea, tension, compression, and allodynia. For this polymorphism, GT heterozygotes and TT homozygotes were significantly higher in the migraine group than in the control group (OR 3.027 and 95 % CI 1.830-5.008 and OR 3.221 and 95 % CI 1.223-8.484, respectively). The G10T genotype was correlated with attack duration and age at the onset of migraine (p = 0.008 and p = 0.040). eNOS polymorphisms may be useful markers for assessing migraine risk and clinical diagnosis.

Pharmacogenomics of episodic migraine: time has come for a step forward

Migraine is characterized by heterogeneous behavior in response to drugs. Many resources have been invested in attempting to unravel the genetic basis of migraine, while the role of genetics in responses to currently available drugs has received less attention. We performed a systematic literature search identifying original articles pertaining to pharmacogenomics of episodic migraine. Few primary studies on the pharmacogenomics of symptomatic and preventive medication in episodic migraine were found. The number of patients studied in the individual articles ranged from 40 up to 130. There was a strong heterogeneity among these studies. We believe that pharmacogenomics studies, if properly designed, could contribute towards optimizing the treatment and reducing the burden of migraine, in turn helping patients and optimizing resources. Our knowledge on the pharmacogenomics of migraine is growing too slowly, and concerted measures should be undertaken to speed up the process.

Shorter telomere length in peripheral blood cells associated with migraine in women

OBJECTIVE

To evaluate relative telomere length of female migraine patients.

BACKGROUND

Migraine is a debilitating disorder affecting 6-28% of the population. Studies on the mechanisms of migraine have demonstrated genetic causes but the pathophysiology and subcellular effects of the disease remain poorly understood. Shortened telomere length is associated with age-related or chronic diseases, and induced stresses. Migraine attacks may impart significant stress on cellular function, thus this study investigates a correlation between shortening of telomeres and migraine.

METHODS

Relative telomere length was measured using a previously described quantitative polymerase chain reaction method. A regression analysis was performed to assess differences in mean relative telomere length between migraine patients and healthy controls.

RESULTS

The leukocyte telomeres of a cohort of 142 Caucasian female migraine subjects aged 18-77 years and 143 matched 17-77-year-old healthy control Caucasian women were examined. A significantly shorter relative telomere length was observed in the migraine group compared with the control group after adjusting for age and body mass index (P = .001). In addition, age of onset was observed to associate with the loss of relative telomere length, especially at early age of onset (<17 years old). No association was observed between relative telomere length and the severity and frequency of migraine attacks and the duration of migraine.

CONCLUSION

Telomeres are shorter in migraine patients and there is more variation in telomere length in migraine patients.

Pathways to the Best Fit of Triptans for Migraine Patients

Variability in drug response is a major barrier to the successful treatment of migraine, and most treatments are only optimal in a subset of patients. Although triptans provide the best therapeutic option for the treatment of acute migraine, it has not previously been possible to predict how well patients will respond to a specific triptan or whether they will experience unpleasant adverse events. Hence, it has been difficult for physicians to match individual patients with the most suitable agent to treat their migraine pain. Intrapatient variability has been associated with polymorphisms in genes encoding drug-metabolizing enzymes, drug transporters and drug targets. Pharmacogenetics provides the possibility of tailoring the therapeutic approach to individual patients, in order to maximize treatment efficacy while minimizing the potential for unwanted side-effects. This review demonstrates how almotriptan may overcome genetically determined responses by utilizing diverse metabolic pathways to provide therapeutic benefit to many migraineurs.

Genetics of migraine and pharmacogenomics: some considerations

Migraine is a complex disorder caused by a combination of genetic and environmental factors. Although family and twin studies show that there is a genetic component in migraine, no genes predisposing to common forms of the disorder, migraine with and without aura, have been identified. Patients with migraine respond differently to a given drug administered. The efficacy of therapy and the occurrence of adverse drug response are a consequence of individual variability. Genetic profiling of predisposition to migraine should facilitate the development of more effective diagnostic and therapeutic applications. The development of International Hap Map project could provide a powerful tool for identification of the candidate genes in this complex disease and pharmacogenomics research could be the promise for individualized treatments and prevention of adverse drug response.