Thrombophilic gene mutations in children with migraine

Abstract

In 35 patients of both sexes (18 boys and 17 girls), mean age 8.9 ± 4.5 years, affected by migraine both with (45.2%) and without an aura (54.9%) (P > 0.05) who had no alteration of brain computerized tomography and/or magnetic resonance imaging, we evaluated possible thrombotic events in the pathogenesis of the disease. In all cases and in 50 random healthy controls clotting tests (prothrombin time, activated partial thromboplastin time, protein C activity (PC), antithrombin III (ATIII), protein S (PS), antiphospholipid antibodies (aPL), and Lupus anticoagulant (LA) were normal. FVIII and FIX activities were increased in seven and five migraine sufferers, respectively. Genetic thrombophilic risk factors – factor V Leiden (FVL) and MTHFR677T – resulted in a significantly increased prevalence in migraine patients when compared with controls but without significant differences for the F2 polymorphism. The examined polymorphisms were associated with an increased risk of developing migraine (odds ratio (OR) > 1). These findings could confirm the key role of a reduced cerebral flow in the pathogenesis of migraine and possible risk of ischaemic stroke (IS) but we feel that these observations need to be confirmed in larger multi-centre studies.

Keywords:

• Migraine
• Genetic thrombophilic risk factors
• FVL
• F2
• MTHFRC677T

Introduction

Migraine represents the most important and frequent type of headache in the paediatric population. The association between migraine and stroke has been reported in both children and adults, and this has been highlighted particularly in cases of migraine with an aura; however, what links the two is currently unknown.^1,2 However, it has been suggested that during attacks of migraine both platelet activation and plasma coagulability are increased.^3,4

Over the last few years, genetic factors involved in thrombophilic events have been studied both in adults⁴ and in children suffering from migraine,⁵ but the reports have been limited and the conclusions are controversial.

We investigated, by a retrospective study (from 2002 to 2010), the prevalence of some genetic thrombophilic risk factor mutations in paediatric and adolescent populations suffering from migraine.

Materials and methods

Thirty-five Italian outpatients – from Campania region – aged between 7.5 and 14.5 years (mean age 8.9 ± 4.5 years) of both sexes (18 boys and 17 girls) affected by recurrent migraine were included in the study. Diagnosis of migraine was performed according to the International Headache Society Criteria for paediatric migraine.

In each case, the presence or absence of an aura was investigated. Apart from the migraine the children were healthy. Brain computerized tomography and/or magnetic resonance imaging were performed and found normal in all those suffering from migraine.

The following clotting tests were analysed: prothrombin time, activated partial thromboplastin time, fibrinogen, protein C activity (PC), antithrombin III (ATIII), protein S (PS). Antiphospholipid antibodies (aPL) in classes IgA, IgM, and IgG (enzyme-linked immunosorbent assay), and Lupus anticoagulant (LA) were studied. Coagulation factors VIII and IX were determined.

The genetic thrombophilic risk factors investigated included whether a mutation at nucleotide position G1691A of factor V gene (factor V Leiden, FVL) was present or absent as described by Ridker et al.,⁶ the presence or absence of prothrombin G20210A mutation (F2) as described by Iwahana et al.⁷ and MTHFR C677T polymorphism was also determined in patients and controls as described by Frosst et al.⁸

Comparison of data was drawn with 50 random healthy controls aged between 9 and 15 years (mean age 10.5 ± 3.2 years).

Family history of headache and thrombotic events was obtained from patients and controls.⁹ Informed consent was obtained from parents. The principles outlined in the Declaration of Helsinki were followed. Statistical analysis was performed: patient and control data were compared using the χ² test. A P value ≤ 0.05 was considered statistically significant.

The strength of the association between genetic thrombophilic mutations and occurrence of migraine was estimated by calculating the odds ratio (OR). Values >1 were considered as a positive association with the disease, while <1 as protective against the same.

Results

No significant differences were found between migraine sufferers with (45.2%) and without an aura (54.9%). (P > 0.05) (Table 1). The values of FVIII and FIX were higher than normal in seven and five patients, respectively. Four of these patients show higher values of both FVIII and FIX (Table 1). No significant differences of FVIII and FIX were found between patients with and without an aura. None of the controls had higher values of FVIII and FIX (Table 1).

Table 1. Characteristics of those with migraine compared with controls

	N* (%)	Gender (M/F)	Age ± SD	↑FVIII (>150 U/ml)	↑FIX (>160 U/ml)
Migraine patients	42	18/24	8.9 ± 4.5	7	5
With aura*	19 (45.2%)	9/10	9.2 ± 3.1	6	1
Without aura*	23 (54.7%)	9/14	7.9 ± 4.7	1	1
Controls	50 (100%)	22/28	10.5 ± 3.2	–	–

*P > 0.05.

Routine clotting tests, ATIII, PC, and PS activity result were all normal, as well as aPL in classes IgA, IgM, and IgG, whose mean values in patients do not differ significantly from controls (data not shown). LA was absent in all patients.

Family history of headache and occurrence of thrombotic events in parents and relatives of migraine patients and controls (150 and 210, respectively) showed that 53 and 9.5%, respectively, had headache (P < 0.05), while 9% of patients’ parents only had thrombophilic events (data not shown).

Prevalence of genetic mutations of FVL, F2, and MTHFR C677T in patients and controls are reported in Table 2.

Table 2. Rate of genetic mutations in patients and controls, and OR evaluation

	Patients (42)	Controls (50)	OR	CI
FVL*	9 (21.4%)	2 (4%)	7.5	−0.77 + 0.97
F2	5 (11.9%)	3 (6%)	2.1	−0.18 + 0.48
MTHFR*	15 (35.7%)	5 (11.9%)	5	−0.56 + 0.82

*P < 0.05.

The rate of homozygous FVL and MTHFR C677T polymorphisms were significantly higher in patients than in controls (P < 0.05), while no significant differences were found for homozygous F2 polymorphisms (P > 0.05). In two patients we found both homozygous mutations MTHFR C677T and FVL (Table 2).

OR was evaluated for the association of each genetic mutation with migraine: examined polymorphisms result associated with increased risk of migraine (OR > 1) (Table 2). No significant differences were found in the rate of genetic mutations between patients with and without an aura (Table 3).

Table 3. Rate of thrombophilic factors in migraine sufferers with and without an aura

	Migraine with aura (19)	Migraine without aura (23)
FVL*	7	3
F2*	4	1
MTHFR*	9	6

*P > 0.05.

Discussion

The mechanisms underlying the association between migraine and ischaemic stroke (IS) is not understood.

The association is more common in adults than in childhood, although the relationships between migraine and IS have been increasingly reported in recent years.^10,11 More recently, coagulation abnormalities in migraine and IS have been reported and a link between these two conditions has been suggested.¹² In addition, a study on the flow in orbital and vertebral arteries in patients with migraine without an aura has shown decreased vascular flow velocity not only during migraine episodes, but also in migraine patients during headache free-periods compared with healthy controls, suggesting possible vascular involvement and autonomic dysfunction in the patients.¹³

These findings confirm that the cerebral flow could play a key role in the pathogenesis of migraine. It has also been suggested that the reduction of cerebral microvascular bed could be related to clotting alterations.⁵ An association between aPL and migraine has been studied in childhood, but the results are controversial. Some studies have not found significant association,¹⁴ while, more recently, other investigators have shown significant increase of aPL in migraine sufferers.² Our data show that, in children with migraine, aPL does not differ significantly from controls (data not shown).

Moreover, in some patients we found increased values of F VIII and F IX in agreement with other reports.⁵ It has been suggested that the increase of these clotting factors could be the result rather than the cause of the migraine and, particularly, the increase of FVIII could be linked to activated PC.⁵

Most recent studies on the relationship between genetic mutation of FVL, F2, MTHFR C677T, and migraine are also controversial. A high prevalence of FVL has been reported in migraine sufferers with an aura, but this association was not statistically significant. Furthermore, the same investigators found that the other prothrombotic genetic factors were not associated with migraine and hypercoagulability.⁴ In agreement with this report further studies have not found a relationship between genetic thrombophilic factors and hypercoagulability in migraine.¹⁵ More recently, Kutai et al.⁵ reported a significant relationship between FVL and migraine in Jewish patients (P < 0.005), but the data were not significant in Arab patients. Furthermore, the investigators did not find a significant relationship between F2 and MTHFR C677T polymorphisms and migraine in either Arab or Jewish patients.

Our findings show significant relationships of both FVL and MTHFR polymorphisms with the presence of migraine. Furthermore, we found that genetic thrombophilic factors represent risk factors for developing migraine (OR > 1).

We think in agreement with other reports^5,13 that the reduction of microvascular cerebral flow plays a crucial role in determining the migraine. The presence of thrombophilic factors could enhance the risk of thrombotic events. It is possible that some genetic mutations influence microthrombotic events and it might be an additional risk factor in patients with migraine who subsequently could develop IS.

However, the reports on the relationship between genetic thrombophilic factors and migraine in childhood are too few to develop firm conclusions. Our data did not allow a relevant statistical analysis to be carried out.

In summary, we would suggest that the presence of these polymorphisms does not guarantee the development of both migraine or IS, but it ought to be considered as indicators for additional risk of these events. Our findings, in agreement with other data,^2,4,5 underline the need of multi-centre studies on large populations to confirm these correlations in childhood as well as in adults.