In 2018, a research study performed on a European cohort of over 1000 adult-onset patients with PAH confirmed the presence of potentially causative variants in approximately 19% of the patients in previously well-known associated genes, including BMPR2, TBX4, ACVRL1, ENG, SAMD9, and KCNK3 [10]. The gene discussed is TBX4; the disease is pulmonary arterial hypertension.