Abstract Body (Do not enter title and authors here): Background: Pulmonary Arterial Hypertension (PAH) is a fatal cardiopulmonary disorder characterized by adverse vascular remodelling of small pulmonary arteries, which increases resistance and demand on the right ventricle (RV), ultimately leading to RV fibrosis and failure. Emerging evidence suggests that inflammation plays a crucial role in PAH pathogenesis. Here, we study Clonal Hematopoiesis of Indeterminate Potential (CHIP), a disorder characterized by somatic mutations in genes such as DNMT3A and TET2, that promotes an inflammatory phenotype, in the development of PAH.
Methods: We performed deep, targeted panel sequencing on 1659 PAH patients from the PAH Biobank and 3644 controls (3401 Vanderbilt University Biorepository patients and 243 participants recruited by the Queen’s Genomics Centre at Ongwanada). Variants in known CHIP genes expressed at a variant allele frequency (VAF) >2% were classified as CHIP. Genes with a VAF >25% and <50% were considered CHIP if located in reported CHIP hotspot regions. The prevalence of CHIP mutations was compared between controls and PAH patients. Logistic regression was used for statistical analysis.
Results: We identified 242 CHIP variants in the 1659 PAH patients. DNMT3A was the most mutated gene (116/242 = 48%), followed by TET2 (46/242=19%). After adjusting for age and sex, we identified a significant association between all CHIP variants combined and PAH (OR: 23.35 [7.67, 71.03]; p<0.0001). Further, DNMT3A CHIP (OR: 25.44 [5.37, 120.40]; p<0.0001), non-DNMT3A CHIP (OR: 26.80 [5.56, 129.23]; p<0.0001) and TET2 CHIP (OR: 13.69 [1.29, 145.30]; p=0.03) were all associated with PAH. A higher proportion of PAH patients under the age of 70 were found to have CHIP variants compared to controls and this was significant for individuals between 60-69 years of age (p=0.037). While there was a 3.8:1 female-to-male ratio of PAH patients, there was a 5.8:1 female-to-male preponderance of DNMT3A variants (p=0.039) (4.3:1 for all CHIP; p=ns), suggesting DNMT3A variants are more common in female patients. The presence of CHIP variants had no significant effect on PAH patient 10-year survival.
Conclusion: This research reveals a significant association between CHIP variants, specifically in DNMT3A and TET2, and PAH. The prevalence of CHIP is higher in PAH patients aged 40 to 70 compared to controls and is more common in female patients. These findings suggest that CHIP is a significant risk factor for the development of PAH.