EIF2AK4 and heritable pulmonary arterial hypertension: All living family members with manifest HPAH (II:4, III:2 in Fig. 2) carried a heterozygous mutations in BMPR2 and EIF2AK4. In contrast, two non-diseased family members (III:1 and III:4) carried only the BMPR2 mutation and no mutation in EIF2AK4. None of these family members developed manifest HPAH (Fig. 2) at of the time of this writing.