Subsequently, biallelic EIF2AK4 mutations were also identified in 25% of sporadic PVOD cases [109], 11.1% of HPAH cases (one of nine cases) [110] and 1.04% of I/HPAH cases (nine of 864 cases) [111]. The gene discussed is EIF2AK4; the disease is pulmonary venoocclusive disease.