We also reproduced the effects of GCH1 knockdown, observed in human uterine microvascular endothelial cells, in human primary myometrial endothelial cells, in support of the notion that reduced endothelial cell GCH1 and BH4 are features of pregnancy-related hypertension, and have effects on endothelial cell function and growth. This evidence concerns the gene GCH1 and hypertensive disorder.