Involved in the transcriptional regulation of genes required for mesoderm differentiation. Probably plays a role in limb pattern formation. Defects in TBX4 are the cause of small patella syndrome (SPS); also known as ischiopatellar dysplasia or Scott-Taor syndrome. SPS is an autosomal dominant skeletal dysplasia characterized by patellar aplasia or hypoplasia and by anomalies of the pelvis and feet, including disrupted ossification of the ischia and inferior pubic rami. Note: This description may include information from UniProtKB.