Is CD3G p.Arg166Ter (c.496C>T) pathogenic?

CD3G p.Arg166Ter (c.496C>T) is classified Pathogenic in CD3G (ClinVar, Single submitter, 1 submitter; last evaluated 2026-01-24). Very rare (popmax 0.00446%, eas); Associated with combined immunodeficiency due to CD3gamma deficiency.

What condition is associated with CD3G p.Arg166Ter (c.496C>T)?

CD3G p.Arg166Ter (c.496C>T) is associated with combined immunodeficiency due to CD3gamma deficiency (ClinVar).

How common is CD3G p.Arg166Ter (c.496C>T) in the general population?

CD3G p.Arg166Ter (c.496C>T) is very rare (popmax 0.00446%, eas) (gnomAD).

CD3G p.Arg166Ter

Q: How is Combined immunodeficiency due to CD3gamma deficiency inherited?

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

c.496C>T · rs201529449 · VCV1457956

Pathogenic Single submitter

Classification

Pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.00446%, eas)

Conditions

combined immunodeficiency due to CD3gamma deficiency

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	predicted	premature termination codon in exon 6 of 7
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 2.2	GERP 1.1, phastCons 0.98
Overall
CADD	37.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00446% East Asian · 2/44,884 alleles

Filtering AF 0.000739% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000276%

Overall 0.000558% 9/1,613,858 alleles · very rare

Ancestry group	Frequency	1 in
East Asiangrpmax	0.00446%	22,442
African / African-American	0.00267%	37,495
European (non-Finnish)	0.000424%	235,964

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: CD3G
Protein: p.Arg166Ter
Coding: c.496C>T
MANE Select: NM_000073
dbSNP: rs201529449
Type: single nucleotide variant
Location: chr11:118352416 (GRCh38)
Gene constraint: LOEUF 1.191 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 75.05 · 38 PDB
Residue 166: an α-helix; the itam domain

Full CD3G gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

combined immunodeficiency due to CD3gamma deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Combined immunodeficiency due to CD3gamma deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy

Similar variants

CD3G p.Arg166Gln Uncertain significance ★★ ⚠ same residue
CD3G p.Arg166= Conflicting classifications of pathogenicity ★ same residue
CD3G c.55+1G>T Likely pathogenic ★★ same condition
CD3G c.56-1G>A Likely pathogenic ★★ same condition
CD3G p.Lys69Ter Pathogenic ★★ same condition
CD3G p.Met1Val Pathogenic/Likely pathogenic ★★ same condition
CD3G c.*308G>A Uncertain significance ★★ same condition
CD3G p.Arg146Thr 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/cd3g-p-arg166ter (accessed [today's date]).

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