TBX4 and pulmonary arterial hypertension: Heterozygous SNVs in TBX4 and CNV deletions involving TBX4 and TBX2 have been reported also in pediatric and adult patients with pulmonary arterial hypertension (PAH) [17, 18], ischiocoxopodopatellar syndrome (MIM# 147891), and developmental delay, heart defects, and limb abnormalities [19].