Ischemic cerebrovascular disease caused by genetic mutation and patent foramen ovale

Introduction

Cerebrovascular disease (CVD) is a major cause of disability and the second leading cause of death worldwide [1, 2]. CVD is directly related to genetic mutations, except for systemic diseases, and these mutations are usually in combination. Factor V and MTHFR gene mutations are the most common reported genetic combination in the adult population developing arterial and venous thrombosis. CVD can be seen as arterial, venous, single or multiple, cerebral or spinal events. Detection of mutations is important because it often requires aggressive anticoagulant therapy. It is very important to look for genetic mutations in patients with a family history of CVD who have recurrent cerebral arterial events (CAE), especially in young patients, and in whom other causes have been excluded, in terms of revealing the etiologic cause [3].

Patent foramen ovale (PFO) is an independent risk factor in young patients with cryptogenic CAE and the pathogenic relationship between PFO and CAE is still unclear in most cases [4, 5]. Due to the uncertainty in the mechanism of brain ischemia, secondary protection in stroke with PFO is still an important topic of discussion. Recently, it has been reported that hemostatic system imbalance increases the risk of unstable thrombus formation and affects the risk of cerebral ischemia in the presence of interatrial septal abnormalities. Detection of the hypercoagulability underlying PFO associated CAE is important for understanding the pathophysiological process and determining the most appropriate treatment options [6, 7]. There is no comprehensive research published on this subject. Therefore, the association of PFO with inherited genetic mutations in cases with CAE has not yet been determined.

In this study, we aimed to discuss the characteristics of genetic mutations in the etiology of ischemic stroke and stroke types (arterial or venous events).

Materials and methods

This study was conducted with the approval of Lokman Hekim University Clinical Research Ethics Committee (number: 2023147). We retrospectively analyzed 23 patients with arterial and venous CVD who were admitted to Lokman Hekim Akay Hospital Department of Neurology in the last 1 year (January 2022- January 2023) and whose etiology could not be determined except for genetic mutation. Clinical characteristics, laboratory findings, radiologic examinations and genetic mutations of the patients were recorded. Over 18 years of age (males and non-pregnant females) and with a genetic etiology for recurrent arterial or venous events were included in the study, while those with uncontrolled hypertension, diabetes, dyslipidemia or other comorbidities (polycythemia vera, atrial fibrillation, valvular disease, carotid stenosis, connective tissue disease or malignancy) were excluded.

Blood tests including routine hematology, biochemistry and serological studies (ANA, p-ANCA, c-ANCA, anticardiolipin antibody, homocysteine and hypercoagulability panel), electrocardiography (ECG), echocardiography (ECO), rhythm holter were performed and shown to be normal. After excluding the most common causes of stroke, a genetic thrombophilia panel (MTHFR C677, MTHFR A1298C, Factor II, Factor V, Factor XII, Factor XIII, PAI-1 4G/5G) was performed from all patients, especially in young patients, who had a family history of recurrent ischemic stroke and no cause could be found. Transesophageal ECO (TEE) was performed to detect patent foramen ovale (PFO) or atrial thrombus that may accompany 19 patients who had CAE.

Cranial magnetic resonance imaging (MRI), MR angiography or CT angiography of cerebral and carotid arteries were performed in all patients to detect CAE. MR venography was also performed for diagnosis of the patients that are suspected to have cerebral venous thrombosis (CVT). After imaging, CAE was detected in 19 patients and CVT was detected in 4 patients. Associations between clinical, laboratory and radiologic findings and different genetic mutations were identified. Genetic mutations were grouped according to CVD characteristics (Table 1).

Results

Clinical, laboratory and radiological data of 23 patients with acute cerebral ischemia or cerebral venous thrombosis were evaluated. The patients were between the ages of 18 and 69, median age is 51 (18–69). There were 9 (39.1 %) men and 14 (60.9 %) women. Routine hematological and biochemical studies of all patients were normal. ANA, p-ANCA, c-ANCA, anticardiolipin antibody values were negative. ECG, ECO, Rhythm Holter and Carotid angiography examinations of all patients were normal.

After radiologic imaging, CAE was diagnosed in 19 patients (83 %) and CVT was diagnosed in 4 patients (17 %). While 12 of the patients with CAE had anterior system arterial involvement, 7 had posterior system arterial involvement in MRI. 13 patients had a single lesion and 6 had multiple lesions.

All 23 patients had at least one mutation. The mutated genes were MTHFR C677, MTHFR A1298, FV, PAI, Protrombin, FXII and FXIII. There were 2–4 multiple gene mutations in 19 patients (83 %), and a single mutation was detected in 4 patients (17 %). MTHFR A1298C was detected alone in 7 (36 %) of 19 (83 %) patients with MTHFR gene mutations, MTHFR C677 alone in 6 (32 %) and these two mutations were detected together in 6 (32 %). While the most common MTHFR (89 %) (17/19) mutation was observed in patients with a diagnosis of cerebral arterial ischemia, CVT was present in 11 % (2/19) of patients with this mutation. There was a significant difference in the presence of MTHFR C677 mutation in arterial and venous thrombosis (p=0.037).

Factor V mutation was detected in 6 patients (26.1 %). It was observed together with MTHFR mutation in 5 patients and Factor XII mutation in 1 patient. This mutation caused arterial infarction in 4 patients and venous infarction in 2 patients. No statistically significant difference was found (p=0.270).

While 13 patients (56.5 %) had PAI-1 mutations, it was observed alone in 2 of these patients and as multiple mutations in the other 11 patients. All patients with the combination had the MTHFR mutation. We found that 10 patients (52.6 %) had arterial, 3 patients (75.0 %) had venous infarction in PAI-1 mutations. The difference between the lesion types and the presence of PAI-1 mutation with CVD was not statistically significant (p=0.604).

Prothrombin mutation was seen alone in a patient with CAE. FXII mutation was seen in a patient with CVT and FXIII mutation was seen in a patient with CVT together with other mutations. The association of FXII and FXIII mutations with CVT was not statistically significant (p=0.174).

Tests were performed to determine the effect of genetic mutations on stroke development and types. MTHFR had the highest rate (83 %) of all mutations.

TEE was performed in all 19 patients who underwent CAE. In this retrospective study, patients with CVT did not undergo TEE because PFO was not an etiologic cause. 14 patients with CAE (73.7 %) accompanied PFO and 1 patient had left atrial thrombus accompanying PFO. This patient carried MTHFR C677 and MTHFR A1298C mutations together. The most common mutations associated with PFO were MTHFR and PAI mutations. No significant statistical difference was observed between the type of mutation accompanied by PFO.

Homocysteine levels were found to be high in 8 of 13 patients whose homocysteine was examined. The mean homocysteine level was 15.7 ± 6.7 μmol/L (normal range: 0–12 μmol/L). All patients with high homocysteine levels had MTHFR mutations. It was found that MTHFR C677 (r=0.479, p=0.021) mutation was positively correlated with arterial events, FXII (r=0.465, p=0.025) and FXIII (r=0.465, p=0.025) mutations were positively correlated with venous events (p<0.05).

Discussion

In this study, young patients presenting with acute cerebral ischemia without systemic risk factors and patients with a family history of unknown cause and genetic mutations with recurrent CVD were examined. MTHFR mutation was detected at a higher rate in the study group and MTHFR C677 mutation was found to be moderately degree of lineer correlation with CAE. Thrombosis risk was not associated with the MTHFR A1298 mutation. Studies have shown that this mutation is predisposing for arterial and venous stroke [11, 12]. Arterial stroke was more common here. Increased homocysteine values are usually associated with the MTHFR mutation and increased homocysteine levels predispose to atherosclerosis [1, 13]. In this study, all patients with high homocysteine levels had MTHFR mutations. Contrary to the literature, PAI gene mutation was found to be another cause of arterial thrombosis with the second frequency. It is most commonly associated with MTHFR mutations and may cause arterial and venous thrombosis. The MTHFR and PAI-1 genes are primarily associated with cerebral artery thrombosis [3, 11, 14].

Another genetic mutation is the Factor V mutation. Herein, the Factor V mutation often was seen in combination with the MTHFR gene mutation associated with the formation of arterial and venous thrombosis, which supports previous studies. Factor V and MTHFR gene mutations are the most common reported genetic combination in the adult population developing arterial and venous thrombosis [11, 15].

Prothrombin gene mutation was seen as the sole cause of arterial thrombosis in only one patient. In the literature, this mutation is mostly associated with spinal cord infarction and less frequently with arterial thrombosis but cerebral venous thrombosis was not observed [3, 16, 17]. Our case was a young patient with homozygous mutation who developed arterial stroke.

Factor XII and Factor XIII gene mutations are rare mutations. Strokes associated with this genetic mutations are mostly of arterial and spinal cord rather than venous origin [3]. Contrary to the literature, venous thrombosis were also associated with Factor XII and Factor XIII gene mutations in our study. No spinal cord infarction was observed. These two mutations showed a moderate linear positive correlation in the development of CVT.

Some studies report some thrombophilia disorders in different combinations and in different stroke types but they could not be associated with a specific category [3]. Multiple gene mutations were observed in 83 % of patients with CVD and a single gene mutation in 17 % of patients. It was determined that MTHFR, PAI-1 and Prothrombin gene mutations emerged as the sole cause of thrombosis. This study showed that multiple gene polymorphisms increase the risk of stroke supporting previous studies [11, 15].

PFO is defined as an independent risk factor in young patients with cryptogenic stroke. The prevalence of thrombophilia in the general population is 0.1–20 % while the prevalence of PFO has been reported to be 20–34 %. Interestingly, patients with stroke have a higher prevalence of both conditions and this situation increases the risk of stroke compared to the general population.

It is detected more frequently than non-impaired controls (10–18 %) [4, 18]. Coexistence of thrombophilia and PFO is not uncommon and studies have shown the prevalence of thrombophilia in patients with PFO of 5–31 % [19], [20], [21]. This requires screening patients with PFO for thrombophilia. In a study, recurrent events in PFO related CAE were associated with thrombophilia [6]. In the other study, patients with thrombophilia had a higher rate of recurrent events before PFO closure than those without thrombophilia, independent of shunt severity, presence of atrial septal aneurysm and cardiovascular risk factors [22]. Recent evidences show that PFO closure may be superior to medical treatment in primary prevention of cerebrovascular events in PFO associated genetic mutations [23].

Therefore, patients with risk factor for thrombophilia should be interrogationed for PFO and patients with PFO should be interrogationed for thrombophilia. Patients at high risk for recurrence should be identified and a treatment plan should be made. In this study, the association of PFO and thrombophilia was found especially in patients over 60 years of age who had a family history of unknown etiology and presented with recurrent stroke. Herein, TEE was performed in all CAE patients and PFO was detected in 73.7 % of patients. Since the study was retrospective, TEE was not performed in CVT patients because there was no indication for TEE; therefore, no comparison could be made between the two groups in terms of PFO. However, the detection of genetic mutations after recurrent events in these patients in whom PFO was detected after the first stroke but genetic mutation tests were not performed is an indication that the relationship between PFO and genetic mutation is not coincidental, but this needs to be demonstrated in prospective studies in these patients.

Conclusions

With this study and a review of the literature, genetic mutations alone or in different combinations can be the cause of CVD. It is concluded that gene mutations can increase the risk of CVD when they are multiple. Most CVD are arterial and are most commonly associated with MTHFR, PAI-1 or Factor V gene mutation. MTHFR mutations showed a moderate linear correlation in the development of arterial events, FXII and FXIII mutations in the development of venous events. It has been observed that the association between thrombophilia and PFO may be high in patients who develop CAE and is especially the cause of recurrent events. These two conditions need to be investigated in high risk patients.