Is C8B p.Trp548Ter (c.1643G>A) pathogenic?

C8B p.Trp548Ter (c.1643G>A) is classified Uncertain significance in C8B (ClinVar, Single submitter, 1 submitter; last evaluated 2022-03-12). Very rare (popmax 0.00667%, amr).

How common is C8B p.Trp548Ter (c.1643G>A) in the general population?

C8B p.Trp548Ter (c.1643G>A) is very rare (popmax 0.00667%, amr) (gnomAD).

C8B p.Trp548Ter

c.1643G>A · rs757959349 · VCV2070020

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.00667%, amr)

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	escapes	premature termination codon in the last exon (12 of 12) — the truncated protein is likely expressed. PVS1 input, not an applied code
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.2	GERP 1.9, phastCons 1
Overall
CADD	51.0	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 0.00667% Admixed American · 4/59,986 alleles

Filtering AF 0.00226% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00135%

Overall 0.000342% 5/1,461,564 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.00667%	14,997
European (non-Finnish)	8.48e-05%	1,179,816

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: C8B
Protein: p.Trp548Ter
Coding: c.1643G>A
MANE Select: NM_000066
dbSNP: rs757959349
Type: single nucleotide variant
Location: chr1:56929537 (GRCh38)
Gene constraint: LOEUF 1.18 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 81.99 · 8 PDB
Residue 548: the tsp type-1 2 domain; a disulfide bond; a UniProt-annotated variant site (in c8d2)

Full C8B gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Similar variants

C8B p.Trp548Gly Uncertain significance ★ ⚠ same residue
C8B p.Arg284Ter Pathogenic ★★ same type
C8B p.Arg428Ter Pathogenic ★★ same type
C8B p.Cys508Ter Pathogenic/Likely pathogenic ★★ same type
C8B p.Gln91Ter Pathogenic/Likely pathogenic ★★ same type
C8B p.Trp9Ter Pathogenic ★★ same type
C8B p.Ala21Thr Uncertain significance ★★ ⚠ same type
C8B p.Ala446Val Uncertain significance ★★ ⚠ same type

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/c8b-p-trp548ter (accessed [today's date]).

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