An increased prevalence of mutations in the SRY-Box Transcription Factor 17 gene (SOX-17) and T-box transcription factor gene (TBX4) has been identified in patients who developed PAH after ventricular septal defect repair and patients with pre-tricuspid shunts and Eisenmenger physiology (18–20). This evidence concerns the gene SOX17 and pulmonary arterial hypertension.