Abstract
Objective
To investigate the correlation between migraine in a Chinese population and a 4 base pair (GAGT) insertion/deletion polymorphism (rs35975099) localized near the 3' end of the tumour necrosis factor superfamily 10 gene, TNFSF10.
Methods
Ethnically Han Chinese patients with migraine and healthy control subjects were recruited. TNFSF10 genotype and allele frequencies were determined via polymerase chain reaction and polyacrylamide gel electrophoresis.
Results
Rs35975099 was in Harvey–Weinberg equilibrium in patients with migraine (n = 269) and control subjects (n = 374). There were no significant relationships between allele or genotype frequency and migraine.
Conclusion
There was no functional significance of the TNFSF10 gene polymorphism rs35975099 in migraine pathogenesis.
Introduction
Migraine is a polygenically inherited chronic neurovascular disorder that can negatively impact work, study, daily activities and health-related quality-of-life. The lifetime prevalence of migraine is between 14% and 16%, and it is three times more common in women than in men.1,2 Migraine is clinically classified between two subtypes based on the presence or absence of aura, symptoms of which include hallucinations, paraesthesia, disturbed vision and weakness. Although the pathological mechanism of migraine is unclear, evidence suggests inflammation may be involved.3,4
Tumour necrosis factor (TNF) is a key cytokine involved in inflammatory reactions and inflammation-related hyperalgesia.5 TNF may play a pivotal role in migraine via activation of meningeal nociceptors, reducing threshold cerebral excitability and propagating neuronal hyperexcitability.6,7 The TNF superfamilies (TNFSF) and TNF receptor superfamilies (TNFRSF) have extensive actions in cell differentiation and survival, and in controlling expression of inflammatory cytokines. 8 TNFSF/TNFRSF gene polymorphisms have now been recported in migraine. These include TNF-α 308 G>A, 9 TNF-β 252 A>G, 10 TNFSF7 11 and TNFRSF1B. 12 TNFSF10 has been shown to exert therapeutic efficacy for inflammatory diseases in experimental animal models, 13 suggesting a role in the progression of inflammation. TNFSF10 polymorphisms are also correlated with cancer susceptibility,14,15 but there is no direct evidence that TNFSF10 polymorphism is associated with migraine.
The aim of this study was to investigate the correlation between migraine in a Chinese population and a 4 base pair (GAGT) insertion/deletion polymorphism (rs35975099) localized near the 3' end of TNFSF10.
Patients and methods
Study population
The study enrolled unrelated ethnically Han Chinese patients with migraine, attending the Neurological Outpatient Service, First Affiliated Hospital of Soochow University, Suzhou, China, for diagnosis or follow-up between October 2008 and December 2010. Migraine was diagnosed and classified according to the International Classification of Headache Disorders-II criteria, as recommended by the International Headache Society.16 Ethnically Han Chinese control subjects were recruited from individuals completing a nutritional survey in the same geographical area as the patients. Subjects with migraine, a family history of migraine, or any severe or recurrent headache in direct relatives were excluded. Data regarding tobacco use (more than one cigarette per day for >1 year) and alcohol use (at least one alcoholic drink per week) were recorded for patients and control subjects.
The ethics committee of Soochow University, Suzhou, China approved the study, and all subjects provided written informed consent prior to enrolment.
Genotyping
Peripheral blood (3 ml) was taken from each subject and stored at –20° until use. DNA was extracted from whole blood 17 and polymerase chain reaction (PCR) for TNFSF10 was carried out as described. 18 Primer sequences were: forward 5′- GGCCCTATGTCCAAATAAGGTT-3′; reverse 5′- GTTCTGGGTTGAGTTGTGCTG-3′. PCR cycling conditions were 94℃ for 7 min followed by 35 cycles of 94℃ for 40 s, 60℃ for 40 s and 72℃ for 40 s, and a final extension step at 72℃ for 5 min. PCR products were separated by 7% nondenaturing polyacrylamide gel electrophoresis and visualized by silver staining. Genotype was determined by number and size of bands on the gel. In order to confirm the reproducibility of PCR genotyping, 10% of samples were randomly selected and re-examined by another technician.
Statistical analyses
Hardy–Weinberg Equilibrium (HWE) was analysed by χ2-test. Between-group comparisons of genotypic and allelic distribution were made by χ2-test. Logistic regression analysis (adjusted for sex, age, alcohol and tobacco use, and clinical characteristics) was conducted to obtain odds ratios (ORs) and 95% confidence intervals (CIs) for the correlation between rs35975099 and migraine risk. All statistical analyses were two-sided and performed using SAS statistical software, version 8.0 (SAS Institute Inc., Cary, NC, USA). P-values ≤0.05 were considered statistically significant.
Results
Clinical characteristics of Chinese patients with migraine, included in a study investigating the correlation between the occurrence of migraine and rs35975099, a 4 base pair (GAGT) insertion/deletion polymorphism localized near the 3' end of the tumour necrosis factor superfamily 10 gene (TNFSF10) (n = 269).
Data presented as mean ± SD or n (%).
More than one cigarette per day for >1 year.
At least one drink per week.
cLow, no effect on daily activity; moderate, slight effect on daily activity; severe, severe effect on daily activity.
Logistic regression analysis of genotype and allele frequencies of rs35975099, a 4 base pair (GAGT) insertion/deletion polymorphism localized near the 3' end of the tumour necrosis factor superfamily 10 gene (TNFSF10), in patients with migraine and in healthy control subjects.
Data presented as n (%).
OR, odds ratio; CI, confidence interval.
Adjusted for age, sex, and smoking and drinking status.
Genotype and allele frequencies of rs35975099, a 4 base pair (GAGT) insertion/deletion polymorphism localized near the 3' end of the tumour necrosis factor superfamily 10 gene (TNFSF10), in patients with migraine stratified according to sex, age at onset, family history and migraine subtype (n = 269).
Data presented as n (%).
Ins, insertion; Del, deletion.
No statistically significant between-group differences (P > 0.05; χ2-test).
Discussion
Our study found no association between genotype or allele distribution of the TNFSF10 gene polymorphism rs35975099 and migraine in Chinese patients with migraine.
Migraine is a primary headache disorder with an unclear pathogenesis, although evidence suggests that ∼ 40% of migraine susceptibility is due to multiple genetic factors.19,20 Studies support the involvement of proinflammatory cytokines (especially TNF) in migraine.21,22 Our earlier study revealed a relationship between TNFRSF1B polymorphism and an augmented risk of migraine. 12 TNFSF10 is involved in acute and chronic inflammatory central nervous system disorders 23 and has many functions in the peripheral and central nervous system, including cell death and immune modulation. 24 There is no evidence for a correlation between altered plasma or cerebral spinal fluid TNFSF10 concentrations and migraine, however. The findings of the present study indicate no functional significance for TNFSF10 rs35975099 in migraine susceptibility in a Chinese population, suggesting that TNFSF10 may not play a major role in migraine, in this demographic group.
Our study has several limitations. First, the rate of migraine with aura was 6.3% in the present study, which is significantly lower than the 20% reported by others.25,26 This may be due to between-study differences in population demographics and the possibility of selection bias in our study. Secondly, our study had a relatively small sample size, and further larger scale studies are required.
In conclusion, we have found no major role for the TNFSF10 gene polymorphism rs35975099 in the pathogenesis of migraine.
Footnotes
Declaration of conflicting interest
The authors declare that there are no conflicts of interest.
Funding
This study was funded by Research and Innovation Project for College Graduates in Jiangsu Province (CX09B_032Z).
