Is F9 p.Pro101= (c.303A>G) pathogenic?

F9 p.Pro101= (c.303A>G) is classified Likely benign in F9 (ClinVar, Single submitter, 1 submitter; last evaluated 2023-01-24). Very rare (popmax 0.00176%, sas); Associated with hemophilia B.

What condition is associated with F9 p.Pro101= (c.303A>G)?

F9 p.Pro101= (c.303A>G) is associated with hemophilia B, thrombophilia, X-linked, due to factor 9 defect (ClinVar).

How common is F9 p.Pro101= (c.303A>G) in the general population?

F9 p.Pro101= (c.303A>G) is very rare (popmax 0.00176%, sas) (gnomAD).

How is Hemophilia B inherited?

Typically X-linked recessive (Orphanet). A genetic counselor can assess individual risk for a family.

F9 p.Pro101=

c.303A>G · rs2520762835 · VCV2938492

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00176%, sas)

Conditions

hemophilia B

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.35	GERP -3.3, phastCons 0.002
Overall
CADD	6.966	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00176% South Asian · 1/56,755 alleles

Overall 9.21e-05% 1/1,085,225 alleles · very rare

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: F9
Protein: p.Pro101=
Coding: c.303A>G
MANE Select: NM_000133
dbSNP: rs2520762835
Type: single nucleotide variant
Location: chrX:139541101 (GRCh38)
Structure: AlphaFold pLDDT 80.45 · 57 PDB
Residue 101: a UniProt-annotated variant site (in hemb); the egf-like 1; calcium-binding domain; a disulfide bond

Full F9 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

hemophilia B — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: thrombophilia, X-linked, due to factor 9 defect

For Hemophilia B (Orphanet):

Inheritance: X-linked recessive
Onset: Childhood, Infancy, Neonatal
Prevalence: 1-9 / 100 000 (Europe)

Similar variants

F9 p.Pro101Ala Pathogenic ★★ same residue
F9 p.Pro101Gln Likely pathogenic ★ same residue
F9 c.520+13A>G Pathogenic ★★★ same condition
F9 c.88+1G>A Pathogenic ★★★ same condition
F9 c.88+5G>T Likely pathogenic ★★★ same condition
F9 p.Ala279Thr Pathogenic ★★★ ⚠ same condition
F9 p.Ala337Pro Likely pathogenic ★★★ same condition
F9 p.Ala337Thr Pathogenic ★★★ ⚠ same condition

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/f9-p-pro101 (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown