KLK1 and pulmonary arterial hypertension: The analysis was then repeated using 812 European IPAH cases and significant associations were observed for BMPR2, KLK1 and GGCX. GGCX encodes γ-glutamyl carboxylase and has previously been implicated in coagulation factor deficiencies and vascular calcification [203], but again, never in PAH.