Abstract

Pulmonary arterial hypertension (PAH) is a progressive disease mainly characterised by a widespread obstruction of distal pulmonary arteries [1]. Untreated, this disease rapidly leads to right heart failure, then to death [2]. Heritable PAH (hPAH) represents about 30% of PAH cases, and this category includes familial forms with or without identified mutations, and sporadic forms carrying a mutation. The first genetic abnormalities discovered in hPAH were bone morphogenetic protein receptor-2 (BMPR2) mutations. Loss of function of this receptor results in proliferation of vascular smooth muscle cells and selection of endothelial cell clones resistant to apoptosis [3]. Since, several other mutations have been implicated in PAH. Mutation in the T-box protein 4 (TBX4) gene lead to an autosomal-dominant disorder called “small patella syndrome” or “coxopodopatellar syndrome”, characterised by patellar aplasia and abnormalities of the feet and pelvis [4]. Recently, TBX4 mutation has been reported in childhood-onset PAH [5] and, more rarely, in adults [6, 7].