Interestingly, the US PAH Biobank study confirmed a causative role of TBX4 not only across various age groups (12/266; 4.6%—paediatric-onset; 11/2345; 0.47%—adult-onset) but also across different PH phenotypes: 2 (one adult; one paediatric)/23; 8.7% PAH-CTD, 3 (two paediatric and one adult-onset)/23; 13% PAH-CHD [25]. This evidence concerns the gene TBX4 and pulmonary arterial hypertension.