The NM_000020.3: c.293A>G variant in ACVRL1 is a missense variant predicted to cause substitution of asparagine by serine at amino acid 98 (p.Asn98Ser). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). The computational predictor REVEL gives a score of 0.508, which is neither above nor below the thresholds predicting a damaging or benign impact on ACVRL1 function. Functional assays showed the variant protein to be non-functional (PS3_Supporting; Internal lab contributors). This variant has been reported in 5 probands with a phenotype consistent with HHT (PS4_Strong; PMIDs: 16690726, 18498373, Internal lab contributors). In summary, this variant meets the criteria to be classified as Likely Pathogenic for autosomal dominant hereditary hemorrhagic telangiectasia based on the ACMG/AMP criteria applied, as specified by the ClinGen Hereditary Hemorrhagic Telangiectasia Variant Curation Expert Panel. Approved by Expert Panel:12/12/2025. Evidence used: PS4_Strong, PM2_Supporting, PS3_Supporting (specification version 1.1.0; 12/12/2025).