In addition, as circulating FLT1 can be generated by either alternatively spliced mRNA that is directly translated into soluble FLT1 or post-translational cleavage of membrane-bound FLT1, and both the etiology and severity of liver disease may affect the levels of metalloproteinases and other FLT1 cleavage proteins, it is possible that the differences in plasma FLT1 levels between cohorts may be confounded by the differences in underlying etiology and severity of liver disease between PoPH and non-PoPH cirrhosis subjects across the two cohorts58–60. This evidence concerns the gene FLT1 and Pulmonary arterial hypertension associated with portal hypertension.