The mean age of onset for the carriers of TBX4 mutations in children with PAH is about 4.4–8.6 years old, which is younger than carriers with BMPR2 mutations (Galambos et al., 2019; Zhu et al., 2019; Southgate et al., 2020). The gene discussed is TBX4; the disease is pulmonary arterial hypertension.