ENG and idiopathic pulmonary arterial hypertension: The familial form of IPAH, which accounts for 6% of all cases, shows genetic anticipation, presentation occurring at a younger age in successive generations.8, 9 Mutations in the bone morphogenetic receptor-II gene account for the majority of cases of familial IPAH and 26% of sporadic cases.10 Pulmonary hypertension also occurs in families with hereditary haemorrhagic telangectasia (HHT) caused by mutations in the activin-like kinase 1 (ALK-1) and endoglin genes.11 Taking a careful family history and examining specifically for evidence of HHT is important.