Abstract 9695: RASA3 as a Novel Candidate Gene in Sickle Cell Disease-associated Pulmonary Hypertension and Pulmonary Arterial Hypertension

Abstract

Introduction: Sickle cell disease (SCD)-associated PH is associated with increased mortality when tricuspid regurgitant jet velocity (TRV) is ≥2.5m/s and mPAP is ≥25mmHg on right heart catheterization. RASA3, a ubiquitously expressed GTPase-activating protein, is integral to angiogenesis and maintenance of endothelial barrier function. Hypothesis: Loss of RASA3 leads to the development of PH in patients with SCD-associated PH and PAH. Methods: Cis-eQTLs were queried for RASA3 using whole genome genotype arrays and gene expression profiles from PBMCs of subjects with SCD from 3 cohorts. Genome-wide SNPs near or in the RASA3 gene that may associate with lung RASA3 expression were identified using data from the Genotype-Tissue Expression project, reduced to 9 tagging SNPs for RASA3 and associated with TRV≥2.5m/s and RHC hemodynamics. Associations between the top RASA3 SNP and RHC hemodynamics were tested using whole genome genotype data from subjects in the PAH Biobank. PAECs collected from explanted lungs from patients with IPAH or control lungs were cultured with RASA3 expression evaluated on Western blot. Results: PBMC-derived RASA3 expression was significantly lower in patients with SCD-associated PH using TRV≥2.5m/s and RHC hemodynamics, with significantly higher mortality (Figure 1). The risk allele (T) at rs9525228, an eQTL for RASA3, correlated with PH risk, higher TRV and higher PVR among PBMCs associated with decreased RASA3 expression in patients with SCD-associated PH. The T allele at rs9525228 was significantly associated with increased mPAP (p=0.014), PVR (p=0.041) and mean right atrial pressure (p=0.04) in patients from the PAH Biobank. RASA3 expression was significantly lower in PAECs from patients with IPAH compared to control. Conclusions: RASA3 is a novel candidate gene in SCD-associated PH and PAH, with RASA3 expression appearing to be protective. Further studies are ongoing to delineate the role of RASA3 in PH.