TBX4 and pulmonary arterial hypertension: In this review, we summarized the recent advances in the field of unique PPHVD associated with developmental defects of the heart and lungs, focusing on segmental PH associated with complex CHD, Fontan circulation with single-ventricle CHD, and mutated genes associated with PAH and cardiopulmonary development, namely TBX4 and SOX17.