Abstract
Background
Carotid artery stenosis is a recognized cause of ischemic stroke in older adults but is rare in individuals under 50, where distinct etiologies such as dissection, fibromuscular dysplasia (FMD), or genetic predispositions are often implicated. The role of inherited thrombophilia in young-onset carotid stenosis remains unclear.
Objective
To assess the prevalence and etiologic associations of selected inherited coagulation-related gene variants in young adults with carotid artery stenosis.
Methods
This single-center observational study included 42 patients under 50 years of age with ≥50% extracranial carotid stenosis. Patients were categorized into four etiologic subgroups: dissection/web, atherosclerosis, FMD, and other. Thrombophilia testing included prothrombin G20210A, factor V Leiden, MTHFR C677T/A1298C, PAI-1 4G/5G, factor XIII V34L, and homocysteine levels. Group comparisons were made using Fisher's exact or chi-square tests.
Results
No statistically significant differences were observed in the distribution of thrombophilia-related markers among the etiologic groups. Although PAI-1 4G/5G polymorphism and elevated homocysteine levels were numerically more frequent in the atherosclerosis group, these trends did not reach statistical significance.
Conclusion
In this modestly sized cohort, inherited coagulation-related gene variants did not differ significantly across carotid stenosis subtypes in young adults. Routine broad panel testing may offer limited etiologic discrimination. Instead, a context-driven, selective testing approach especially considering antiphospholipid syndrome may be more appropriate.
Keywords
Introduction
Carotid artery stenosis is a recognized etiology of ischemic stroke, predominantly affecting older persons as a manifestation of atherosclerotic disease. In individuals under 50, carotid artery stenosis is relatively rare and typically linked to specific etiological causes, including arterial dissection, fibromuscular dysplasia, inflammatory vasculopathies, or genetic and metabolic predispositions. Identifying inherited thrombophilia in young patients with carotid stenosis holds clinical significance, as it may influence diagnostic precision, secondary prevention strategies, and long-term management in this distinct population. Recognizing these fundamental mechanisms is essential, as they may affect both immediate care and subsequent preventative initiatives.1,2
Thrombophilia denotes a collection of inherited or acquired conditions that elevate the likelihood of thromboembolic occurrences. Common hereditary thrombophilic markers are the factor V Leiden mutation, prothrombin G20210A mutation, methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms, plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism, factor XIII (V34L) variant, and higher plasma homocysteine concentrations. The function of thrombophilia in venous thromboembolism is well recognized; nevertheless, its impact on arterial thrombosis, especially for extracranial carotid artery disease, remains ambiguous. 3
Prior research on young ischemic stroke cohorts has yielded inconsistent findings concerning the prevalence and clinical significance of thrombophilia markers, and studies particularly addressing young patients with carotid artery stenosis are scarce. The prevalence of specific genetic thrombophilia indicators varies among populations, with particular mutations being more prevalent in the Turkish population, highlighting the necessity for localized data. This study aims to ascertain the incidence of hereditary thrombophilia markers in young individuals with carotid artery stenosis and to investigate potential connections with underlying etiological subtypes, including dissection, atherosclerosis, and fibromuscular dysplasia. As genetic predispositions can demonstrate significant regional and ethnic variation, obtaining population-specific data such as from the Turkish cohort studied here is essential for accurate interpretation and clinical application.
Materials and Methods
Research Methodology
This single center, observational study was performed at the Neurology Department of Selcuk University from January 2021 to June 2025. We used a large language model (ChatGPT, OpenAI, San Francisco, CA, USA) to assist in language editing and improving the clarity of the manuscript. All content, data interpretation, and conclusions were generated and verified by the authors, who remain fully responsible for the work.
Criteria for Patient Selection
We included individuals under 50 years of age diagnosed with carotid artery stenosis during the study period. Carotid artery stenosis is characterized by a luminal narrowing of ≥50% in the extracranial internal carotid artery as observed through vascular imaging. The exclusion criteria included the presence of cardioembolic causes other from atrial fibrillation, active malignancy, systemic inflammatory illness, or insufficient thrombophilia information.
Family history of thromboembolic events was recorded when available from medical records or patient interviews. However, due to the retrospective nature of the study, this information was not systematically available for all patients and therefore not included in the final comparative analysis.
Data Collection
Demographic and clinical characteristics recorded for each patient included:
Age and sex Vascular risk factors (hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, smoking status) Etiological classification (dissection/carotid web, atherosclerosis, fibromuscular dysplasia, or other)
Etiological Classification
Etiology was determined based on clinical assessment and vascular imaging findings (computed tomography angiography or digital subtraction angiography).
Dissection/carotid web was diagnosed according to established radiological criteria. Atherosclerosis was defined by the presence of atherosclerotic plaque and luminal narrowing. Fibromuscular dysplasia was identified based on characteristic angiographic patterns.
Thrombophilia Screening
All patients underwent laboratory testing for the following inherited thrombophilia markers:
Prothrombin G20210A mutation Factor V Leiden mutation MTHFR C677T and MTHFR A1298C polymorphisms PAI-1 4G/5G polymorphism Factor XIII (V34L) polymorphism Plasma homocysteine levels
In this study, protein C, protein S, and antithrombin III levels were not included in the thrombophilia panel, as these tests were not routinely performed in our center during the study period and may be affected by acute-phase reactions and anticoagulant use. Medication use with potential effects on hemostasis (eg, nonsteroidal anti-inflammatory drugs [NSAIDs], antiplatelet agents, anticoagulants) was noted when recorded in medical charts. However, due to the retrospective nature and the focus on genetic markers, we did not include pharmacologic exposures as covariates in the primary analysis.
Genetic analyses were performed using polymerase chain reaction (PCR)-based methods, and plasma homocysteine was measured by high-performance liquid chromatography. Standard internal positive and negative controls were included in each run to ensure assay reliability, and 10% of the samples were randomly retested to verify reproducibility of results. Blood samples for thrombophilia screening, including homocysteine measurement, were collected during routine outpatient follow-up, at least 4 weeks after the index ischemic event and after completion of acute-phase treatment, to minimize the influence of transient metabolic alterations.
All procedures were carried out in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments. Ethical approval was obtained from the Selçuk University Ethics Committee (Approval No: E-70632468–050.01–1079725). As part of this approval, the requirement for written informed consent was waived due to the retrospective and anonymized nature of the study.
Statistical Analysis
Continuous variables will be expressed as mean ± standard deviation, and categorical variables as counts and percentages. Comparisons of thrombophilia marker prevalence between etiological subgroups will be performed using Fisher's exact test or chi-square test, as appropriate. A p-value <0.05 will be considered statistically significant. All statistical analyses were conducted utilising SPSS software, version 25.0 (IBM Corp., Armonk, NY, USA).
Results
The study included 42 patients under 50 years of age with carotid artery stenosis Table 1 The average age of the group was 41.9 ± 6.57 years, with a predominance of males (73.8%). Hypertension was observed in 33.3% of patients, diabetes mellitus in 16.7%, and dyslipidemia in 26.2%. Atrial fibrillation was observed in 9.5% of individuals, whereas 59.5% were either current or previous smokers.
Baseline Demographic and Clinical Characteristics of the Study Population.
The etiological distribution revealed dissection or carotid web in 21.4%, atherosclerosis in 21.4%, and fibromuscular dysplasia in 14.3% of the study cohort. The remaining patients exhibited alternative or indeterminate etiologies.
The thrombophilia panel testing identified diverse frequencies of genetic and biochemical anomalies; yet, no statistically significant variations were detected in the prevalence of these markers among the various etiological groupings (p > 0.05 for all comparisons).
Within the four etiological subgroups; dissection/web (n = 9), atherosclerosis (n = 9), fibromuscular dysplasia (FMD) (n = 6), and other (n = 18) no statistically significant differences were observed in the prevalence of any thrombophilia marker (4 × 2 χ² tests, all p > 0.05): prothrombin G20210A (p = 0.616), factor V Leiden (p = 0.424), MTHFR C677 T (p = 0.277), MTHFR A1298C (p = 0.714), PAI-1 4G/5G (p = 0.694), factor XIII V34L (p = 0.616), and elevated homocysteine (p = 0.424). Pairwise Fisher's exact tests, adjusted using the Benjamini Hochberg FDR correction, revealed no significant differences, with the smallest unadjusted p-value approximately 0.20 for homocysteine, dissection/web versus other. Due to the limited cell counts in various strata, including instances of zero, these analyses lack the capacity to identify small-to-moderate differences; hence, any observed intergroup patterns in Table 2 must be regarded with caution.
Association Between Thrombophilia Markers and Etiological Subgroups of Young Carotid Artery Disease.
Discussion
In this single-center cohort of young adults with carotid artery stenosis, we systematically analyzed a panel of inherited and biochemical thrombophilia markers, including prothrombin G20210A, factor V Leiden, MTHFR C677T and A1298C, PAI-1 4G/5G, factor XIII (V34L), and homocysteine, and evaluated their distribution among etiological subgroups (dissection/web, atherosclerosis, fibromuscular dysplasia, and others). The primary conclusion is that no statistically significant differences were seen among the four groups for any marker when assessed using 4 × 2 chi-square tests, and no pairwise comparisons achieved significance following Fisher's exact testing with false-discovery-rate adjustment. The atherosclerosis subgroup exhibited higher numerical rates of PAI-1 4G/5G and elevated homocysteine levels, while the dissection/web and FMD groups generally demonstrated reduced positive across markers; yet, these tendencies could not survive rigorous statistical analysis.
These findings correspond with the general observation that the impact of hereditary thrombophilia on arterial disease is far weaker than its recognized effect in venous thromboembolism. Mechanistically, numerous studied variations are believed to influence coagulation or fibrinolysis (eg, PAI-1 4G/5G) or vascular biology through methylation pathways (homocysteine/MTHFR). Although these pathways may reasonably affect plaque biology, thrombus progression, or vessel wall integrity, the effect sizes in arterial beds, particularly in extracranial carotid disease among the young, seem modest and are often overshadowed by competing etiologies such as dissection, non-atherosclerotic vasculopathies, and conventional vascular risk factors prevalent in our cohort (eg, smoking and hypertension).4–6
From a clinical standpoint, our findings contest the frequent application of extensive, hereditary thrombophilia panels as an etiological differentiator in young patients with carotid stenosis. A targeted approach appears more justifiable, prioritizing testing under the following conditions: (i) a significant personal or familial history of venous or arterial thrombosis, (ii) recurrent or multi-territorial events lacking an alternative explanation, or (iii) clinical situations where results would influence management, such as suspected antiphospholipid syndrome with ramifications for antithrombotic strategy. 7 We acknowledge that antiphospholipid syndrome (APS), as an acquired thrombophilic condition, is among the few disorders consistently associated with arterial thrombotic events including stroke and large-vessel involvement. Although not included in our testing panel, future studies will aim to incorporate APS-related markers (eg, lupus anticoagulant, anticardiolipin, and β2-glycoprotein I antibodies) to improve etiologic characterization in young-onset carotid disease.
Various methodological factors may account for the lack of statistically meaningful signals. Initially, subgroup sizes were constrained (notably FMD), and numerous cells exhibited minimal or no counts, diminishing statistical power and limiting the applicability of asymptotic tests. Under these circumstances, even modest genuine differences may remain undetected (type II mistake). Dichotomizing homocysteine results in the loss of information; modeling it as a continuous variable, with suitable adjustments for renal function and B-vitamin status, may uncover relationships overlooked by binary thresholds. Third, the “other” group unavoidably consolidates diverse pathways, potentially obscuring marker phenotypic associations. Enhanced phenotyping that incorporates high-resolution vessel-wall imaging (plaque augmentation, intraplaque bleeding, ulceration) or uniform dissection criteria could refine biological signals.
Our statistics, however, provide numerous useful insights. The elevated levels of PAI-1 4G/5G and homocysteinemia in atherosclerosis indicate that prothrombotic/fibrinolytic imbalance and methylation biology may converge with early atherogenesis or plaque thrombogenicity in a specific group of young individuals. In contrast, the diminished marker positive in dissection/web and FMD indicates that structural vessel-wall anomalies, rather than systemic prothrombotic tendencies, are likely predominant in both phenotypes. Although these patterns lack statistical conclusiveness, they can guide hypothesis formulation and sample size determination for forthcoming multicenter investigations that stratify by phenotype in advance.
This study has limitations. It is single-center and modest in size; several subgroup marker cells were sparse, limiting inferential precision. We did not include antiphospholipid syndrome testing, nor proteins C/S or antithrombin, which would broaden the biological scope particularly for arterial thrombosis. Timing of laboratory sampling relative to the index event and to antithrombotic therapy was not standardized in our analysis framework; although the genetic assays are therapy-independent, homocysteine can fluctuate with renal function, diet, and supplementation. Finally, as an observational study, residual confounding by unmeasured vascular or environmental factors is possible.
The strengths encompass a concentrated emphasis on a clearly defined young demographic, systematic phenotypic classification (dissection/web, atherosclerosis, FMD, and others), along with an extensive array of genetic and biochemical markers evaluated with rigorous multiple-testing control. Collectively, these attributes offer an accurate depiction of the efficacy of thrombophilia testing in routine clinical practice for young patients with carotid stenosis and identify areas where it may lack discriminative value.
In conclusion, among four etiological categories of young adults with carotid artery stenosis, we observed no statistically significant correlation between the evaluated thrombophilia markers and disease etiology. The data endorse a selective, context-dependent strategy for thrombophilia assessment, particularly highlighting APS when clinically suspected, while stressing thorough vascular phenotyping and proactive management of modifiable risk factors. We strongly believe that future studies should incorporate multicenter collaboration with larger sample sizes, inclusion of additional thrombophilic markers such as antiphospholipid antibodies and natural anticoagulants, and more advanced vascular imaging techniques. These improvements will be instrumental in refining phenotype classification and elucidating whether distinct coagulation abnormalities underlie specific subtypes of early-onset carotid artery stenosis.
Conclusions
In conclusion, this study did not demonstrate a significant association between inherited thrombophilia markers and specific etiologies of early-onset carotid artery stenosis. While selective abnormalities such as PAI-1 polymorphism and hyperhomocysteinemia appeared numerically higher in the atherosclerotic group, these trends lacked statistical significance. These findings support a more tailored approach to thrombophilia testing in young patients, focusing on those with suggestive clinical features or recurrent events rather than routine broad panel screening.
Footnotes
Author Contributions Statement
Ebru Marzioglu Ozdemir conceived and designed the study. Gokhan Ozdemir contributed to the neurological evaluation and interpretation of clinical data. Ebru Marzioglu Ozdemir collected patient data and performed the genetic analyses. Ebru Marzioglu Ozdemir conducted the statistical analyses and prepared the tables. Ebru Marzioglu Ozdemir and Gokhan Ozdemir drafted the manuscript. All authors critically revised the manuscript for important intellectual content, approved the final version, and agree to be accountable for all aspects of the work.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
