Additional HHT-related pathologies include pulmonary arterial hypertension (PAH) when the prognosis appears worse than for patients with PAH due to BMPR2 mutations [17], a higher risk of venous thromboemboli (enhanced in the setting of iron deficiency) [18,19], and for patients with SMAD4 mutations, colon cancer and other gastrointestinal cancers related to their juvenile polyposis [20,21]. Here, SMAD4 is linked to pulmonary arterial hypertension.