Is TAPBP p.Phe256= (c.768C>T) pathogenic?

TAPBP p.Phe256= (c.768C>T) is classified Likely benign in TAPBP (ClinVar, Multiple submitters, 2 submitters; last evaluated 2026-02-01). Ultra-rare (popmax 0.0825%, mid); Associated with MHC class I deficiency.

What condition is associated with TAPBP p.Phe256= (c.768C>T)?

TAPBP p.Phe256= (c.768C>T) is associated with MHC class I deficiency (ClinVar).

How common is TAPBP p.Phe256= (c.768C>T) in the general population?

TAPBP p.Phe256= (c.768C>T) is ultra-rare (popmax 0.0825%, mid) (gnomAD).

TAPBP p.Phe256=

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.768C>T · rs145473025 · VCV771713

Likely benign Multiple submitters

Classification

Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

gnomAD v4.1

Rare

ultra-rare (popmax 0.0825%, mid)

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 1.6	GERP -1.7, phastCons 1
Overall
CADD	9.734	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0825% Middle Eastern · 5/6,062 alleles

Filtering AF 0.0673% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.0618%

Overall 0.0197% 318/1,614,220 alleles · ultra-rare

Ancestry group	Frequency	1 in
Middle Easterngrpmax	0.0825%	1,212
South Asian	0.0823%	1,214
Admixed American	0.0333%	3,001
Remaining individualsnot grpmax-eligible	0.0304%	3,290
European (non-Finnish)	0.0165%	6,052
African / African-American	0.00533%	18,763

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.Phe256=
Coding: c.768C>T
MANE Select: NM_003190
dbSNP: rs145473025
Type: single nucleotide variant
Location: chr6:33305089 (GRCh38)
Gene constraint: LOEUF 1.061 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 87.71 · 12 PDB
Residue 256: 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.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
TAPBP p.Ala433Thr Uncertain significance ★★ ⚠ same condition
TAPBP p.Arg208Cys 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-phe256 (accessed [today's date]).

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