#2709 Genome wide association study regarding disturbed AVF patency
Authors: Hofmann Amun Georg , Leinweber Maria-Elisabeth , Wielscher Matthias 
Published: May 2024

Abstract

Background and Aims
Veins are frequently exposed to arterial circulation, as coronary artery bypass grafts (CABG) and as a peripheral venous bypass to treat atherosclerotic disease, or in the case of arterio-venous fistulas (AVF) to provide a vascular access for hemodialysis. Therapeutic success is dependent on proficient venous remodeling after introduction in the arterial circulation to sustain the increased hemodynamic pressure. Frequently observed adverse outcomes after the aforementioned procedures include the stenosis or total occlusion of the vein, requiring surgical or interventional treatment or leading to bypass/ AVF failure. Hereditary factors associated with disturbed venous patency have been previously investigated in all three conditions. For example, distinct VEGF-A as well as TGF-beta polymorphisms have been identified to correlate with AVF failure.
In the present analysis we aimed at investigating whether genetic polymorphisms associated with disturbed venous patency after AVF creation are similar to findings in CABG and peripheral bypass patients in a genome wide association study.

Method
The analyses were conducted in White Europeans (N= 425,406) in the UK Biobank using regenie software. This software employs a linear mixed model that accounts for the impact of population structure and individual relatedness. Out of approximately 805,000 variants, we selected 606,201 high-quality variants to construct a relatedness model for regenie. These selected variants were identified by a genotyping rate exceeding 80%, minor allele frequencies greater than 1%, and Hardy-Weinberg equilibrium p-values below 10^-8. We adjusted for age, sex, BMI, smoking, and history venous thromboembolism. We assessed the association of 9,757,417 imputed SNPs, each having a minimum allele count of 12 and a minimum info score of 0.3.

Results
In total, 768 patients underwent at least 1 surgery for AVF creation. Out of those, 341 (44.4%) had a recorded procedure or diagnosis associated with disturbed fistula patency. The controls included 6067 CABGs and 384 peripheral bypasses with 76 (1.3%) and 67 (17.4%) recorded events, respectively. We found no genome wide significant associations for the tested SNPs and patency-related AVF complications (Fig. 1). Additionally, we also found no genome wide significant associations after combining the phenotypes (Fig. 2).

Conclusion
Multiple studies have evaluated genetic associations and adverse clinical outcomes after AVF creation. Nevertheless, the generalizability of these findings might be limited at least partially due to small sample sizes. While the sample size of the present analysis is similar to previous research efforts and therefore also comparably low, the lack of consistency in results might be suggestive of the difficulties research in this field faces. Additionally, we found no indication that impaired venous patency after AVF creation is related to complications after coronary or peripheral bypass surgery regarding genetic patient profiles. However, whether this is due to differences in pathophysiology and related genetic predispositions or due to the limited sample size and incidence rates of the present study remains to be determined in follow-up investigations.