Scientists have identified a new serum biomarker called NOTCH3 extracellular domain (NOTCH3-ECD), which enables reliable diagnosis of idiopathic pulmonary arterial hypertension and its differentiation from other forms of pulmonary hypertension and healthy individuals[4]. NOTCH3-ECD blood levels achieve the same accuracy as current standard clinical tests in predicting disease progression and risk of death[4]. This biomarker represents a potential advance in the diagnosis and monitoring of this serious lung disease[4]. The research was published in the journal Nature Medicine on January 9, 2026[4]. Findings suggest that measurement of NOTCH3-ECD serum levels could improve early disease detection and follow-up in patients[4].