As PoPH nuclei demonstrated a pattern of differential gene expression involving the BMPR2, ESR1, and FLT1 genes, we then sought to validate this pattern of gene expression using immunohistochemistry staining of human liver tissue from PoPH, non-PoPH cirrhosis, and normal liver tissue samples. Here, FLT1 is linked to Pulmonary arterial hypertension associated with portal hypertension.