BMPR2 c.1259G>T is a missense variant predicted to cause substitution of cysteine to phenylalanine at amino acid position 420 (p.Cys420Phe). The variant is absent from gnomAD v2.1.1 and v4.1 (PM2_supporting). A REVEL score of 0.914 meets PP3_supporting (>0.75). The variant resides in the conserved catalytic kinase domain but does not affect a known critical residue (PM1_moderate). The variant has been reported in two unrelated PAH probands, one heritable (PMID: 27453251) and one idiopathic (PMID: 30578397, 32634488) (PS4_supporting). A different missense variant at the same amino acid residue, p.Cys420Arg (PMID: 11115378, 21801371) was classified by the PH VCEP as pathogenic (PM5_moderate). In summary, this variant meets the criteria to be classified as a likely pathogenic variant for pulmonary arterial hypertension based on the ACMG/AMP criteria applied, as specified by the ClinGen Pulmonary Hypertension VCEP: PM1_moderate, PM5_moderate, PS4_supporting, PM2_supporting, PP3_supporting (VCEP specification version 2.0, 1/30/2026).