Such "false negatives" also were seen in a study from the Royal Free Hospital in the UK, which showed an NT-proBNP cut-point value of 395 pg/ml to have a sensitivity of 69% for PAH in a pilot study; this cut-point value was then separately tested in a larger prospective case-control study that produced a sensitivity of only 55.9% [20,25]. This evidence concerns the gene NPPB and pulmonary arterial hypertension.