Variants in this region are associated with HHT2, increased incidence of pulmonary arterial hypertension88–90, and other ALK family-associated diseases such as brachydactyly type A2 (ALK6)91,92 and Loeys-Dietz syndrome (ALK5)93,94. The gene discussed is TGFBR1; the disease is Loeys-Dietz syndrome.