The c.1048T>G variant in F9 is a missense variant predicted to cause substitution of Serine by Alanine at amino acid 350 (p.Ser350Ala). This variant has been reported in 1 proband meeting phenotypic criteria for mild Hemophilia B. However, PS4_Supporting cannot be applied because more than 3 males in gnomAD v2.1.1 are reported with this variant, as per CFD VCEP specifications (PMID: 23492913). The highest population minor allele frequency in gnomAD v2.1.1 is 0.0006494 (9/13858 alleles) in the East Asian population, which is higher than the ClinGen Coagulation Factor Deficiency VCEP threshold (>=0.0000556) for BA1, and therefore meets this criterion (BA1). The computational predictor REVEL gives a score of 0.291, which is below the threshold (<= 0.3) and the splice site predictor Splice AI indicated that the variant has no impact on splicing (score = 0,0,0,0), evidence that does not predict a damaging effect on F9 function (BP4). In summary, this variant meets the criteria to be classified as Benign for Hemophilia B based on the ACMG/AMP criteria applied, as specified by the ClinGen Coagulation Factor Deficiency VCEP (version 1.0.0, released 10/5/2023): BA1, BP4.