The presence of a biallelic EIF2AK4 mutation is sufficient to confirm the diagnosis of PVOD without the need for dangerous lung biopsy for histological confirmation.[1] Therefore for a PAH patient with clinical suspicion of PVOD, biallelic EIF2AK4 variant testing is recommended, regardless of familial history.[14] The discovery of biallelic EIF2AK4 mutations raised the possibility of rapid molecular diagnosis for PVOD. The gene discussed is EIF2AK4; the disease is pulmonary venoocclusive disease.