This finding suggests that the 5-HT2B receptor is not essential for survival in humans.1 Conversely, only 50% of Htr2b knockout mice survive their first postnatal week, since the 5-HT2B receptor plays a key role in the differentiation of cranial neural crest cells5 and heart development.6 The 5-HT2B receptor has also been shown to be required to form experimental tumors in nude mice,7 and for the development of pulmonary hypertension through bone-marrow contribution,8 which suggest a potential preventive role of the HTR2B Q20* in some somatic diseases. This evidence concerns the gene HTR2B and pulmonary arterial hypertension.