Among 41 reported variants of EIF2AK4 gene associated with classic PAH (i.e., non-PVOD PAH), none of them are located in exon 12 of the gene (48); while among 32 reported variants of EIF2AK4 associated with PVOD or pulmonary capillary hemangiomatosis, only 2 of them are located in exon 12, including 1 missense variant at amino acid 643 (31), suggesting that most of the reported mutations of EIF2AK4 associated with PAH or PVOD are not related to exon 12 in the essential kinase domain. Here, EIF2AK4 is linked to pulmonary arterial hypertension.