TBX4 encodes a T-box transcription factor with essential roles in embryonic development of multiple organ systems, particularly the lungs, skeletal system, and limbs. As a DNA-binding transcriptional regulator, TBX4 controls gene expression programs critical for proper organogenesis 1. The protein functions within the PITX1-TBX4 transcriptional pathway, which is uniquely expressed in hindlimb development and helps explain the foot and skeletal phenotypes associated with TBX4 mutations 2. Recent ChIP-seq studies reveal that TBX4 directly regulates genes involved in extracellular matrix organization, actin cytoskeleton, cell migration, and various signaling pathways including serine/threonine kinase and GTPase-mediated signaling 3. TBX4 also interacts with other developmental pathways, including potential crosstalk with SHH-FOXF1 signaling during lung morphogenesis 4. Clinically, TBX4 variants are definitively associated with pulmonary arterial hypertension (PAH), representing the second most common cause of heritable PAH, particularly in pediatric cases 56. Patients with TBX4 variants typically present with milder PAH phenotypes compared to other PAH-associated gene mutations 7. The gene is also linked to broader respiratory diseases and developmental disorders affecting skeletal structures, reflecting its fundamental role in embryonic patterning and organ development 17.