PAH and pulmonary arterial hypertension: p.Asn167Tyr and p.Thr200Asn PAH proteins showed residual enzymatic activity similar to WT PAH (97.8% ± 27.1% and 92.4% ± 25.9%, respectively) and p.Ile406Met exerted 84.6% ± 48.4% of WT PAH activity.