G C A T T A C G G C A T genes Review ‘There and Back Again’—Forward Genetics and Reverse Phenotyping in Pulmonary Arterial Hypertension Emilia M. Swietlik 1,2,3, Matina Prapa 1,3, Jennifer M. Martin 1 , Divya Pandya 1, Kathryn Auckland 1 , Nicholas W. Morrell 1,2,3,4 and Stefan Gräf 1,4,5,* 1 Department of Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK;
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[email protected] (N.W.M.) 2 Royal Papworth Hospital NHS Foundation Trust, Cambridge CB2 0AY, UK 3 Addenbrooke’s Hospital NHS Foundation Trust, Cambridge CB2 0QQ, UK 4 NIHR BioResource for Translational Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK 5 Department of Haematology, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0PT, UK * Correspondence:
[email protected] Received: 26 October 2020; Accepted: 23 November 2020; Published: 26 November 2020 Abstract: Although the invention of right heart catheterisation in the 1950s enabled accurate clinical diagnosis of pulmonary arterial hypertension (PAH), it was not until 2000 when the landmark discovery of the causative role of bone morphogenetic protein receptor type II (BMPR2) mutations shed new light on the pathogenesis of PAH. Since then several genes have been discovered, which now account for around 25% of cases with the clinical diagnosis of idiopathic PAH. Despite the ongoing efforts, in the majority of patients the cause of the disease remains elusive, a phenomenon often referred to as “missing heritability”.