Is TAPBP p.Arg303= (c.909G>A) pathogenic?

TAPBP p.Arg303= (c.909G>A) is classified Likely benign in TAPBP (ClinVar, Single submitter, 1 submitter; last evaluated 2025-05-07). Very rare (popmax 0.00034%, nfe); Associated with MHC class I deficiency.

What condition is associated with TAPBP p.Arg303= (c.909G>A)?

TAPBP p.Arg303= (c.909G>A) is associated with MHC class I deficiency (ClinVar).

How common is TAPBP p.Arg303= (c.909G>A) in the general population?

TAPBP p.Arg303= (c.909G>A) is very rare (popmax 0.00034%, nfe) (gnomAD).

TAPBP p.Arg303=

Q: How is Immunodeficiency by defective expression of MHC class I inherited?

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

c.909G>A · VCV3694821

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00034%, nfe)

Conditions

MHC class I deficiency

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 7.6	GERP 1.7, phastCons 1
Overall
CADD	12.25	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00034% European (non-Finnish) · 4/1,176,346 alleles

Filtering AF 8e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 5.4e-05%

Overall 0.000251% 4/1,594,948 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: TAPBP
Protein: p.Arg303=
Coding: c.909G>A
MANE Select: NM_003190
Type: single nucleotide variant
Location: chr6:33304598 (GRCh38)
Gene constraint: LOEUF 1.061 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 87.71 · 12 PDB
Residue 303: the ig-like c1-type domain; a β-strand

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

Disease context

MHC class I deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Immunodeficiency by defective expression of MHC class I (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood

Similar variants

TAPBP p.Arg303Gln Uncertain significance ★★ ⚠ same residue
TAPBP p.Arg303Trp Conflicting classifications of pathogenicity ★ ⚠ same residue
TAPBP p.Ala191Thr Uncertain significance ★★ ⚠ same condition
TAPBP p.Ala220Val Uncertain significance ★★ ⚠ same condition
TAPBP p.Ala305Ser Uncertain significance ★★ ⚠ same condition
TAPBP p.Ala305Thr Uncertain significance ★★ ⚠ same condition
TAPBP p.Ala309Glu Uncertain significance ★★ ⚠ same condition
TAPBP p.Ala396Thr Uncertain significance ★★ ⚠ 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/tapbp-p-arg303 (accessed [today's date]).

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