Is BBX p.Arg291Cys (c.871C>T) pathogenic?

BBX p.Arg291Cys (c.871C>T) is classified Uncertain significance in BBX (ClinVar, Single submitter, 1 submitter; last evaluated 2023-06-02). AlphaMissense: likely benign (0.0869); Very rare (popmax 0.00401%, afr).

How common is BBX p.Arg291Cys (c.871C>T) in the general population?

BBX p.Arg291Cys (c.871C>T) is very rare (popmax 0.00401%, afr) (gnomAD).

What do computational predictors say about BBX p.Arg291Cys (c.871C>T)?

AlphaMissense predicts likely benign (score 0.0869) — an in-silico prediction, not a clinical call.

BBX p.Arg291Cys

c.871C>T · rs761415898 · VCV2555323

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.0869 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00401%, afr)

Missense predictors

1/3 damaging

AlphaMissense, REVEL, SaProt

Computational evidence

Protein change
AlphaMissense	0.0869	likely benign
REVEL	0.663	pathogenic-leaning
SaProt	LLR -8.44	tolerated
⇒ REVEL calls this damaging; AlphaMissense and SaProt do not.
Splicing
SpliceAI	Δ0.26	acceptor loss · deltas
Constraint at this position
Conservation	phyloP 7.7	GERP 2.9, phastCons 1
Regional constraint	o/e 1.00	unconstrained · MANE · 23 kb · p 0.99 · regional, not allelic
Overall
CADD	26.4	PHRED · no single calibrated threshold — expert panels disagree

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00401% African / African-American · 3/74,890 alleles

Filtering AF 0.00106% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000605%

Overall 0.00124% 20/1,613,728 alleles · very rare

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.00401%	24,963
Admixed American	0.00167%	59,990
European (non-Finnish)	0.00127%	78,657
South Asian	0.0011%	91,080

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: BBX
Protein: p.Arg291Cys
Coding: c.871C>T
MANE Select: NM_001142568
dbSNP: rs761415898
Type: single nucleotide variant
Location: chr3:107755643 (GRCh38)
Gene constraint: LOEUF 0.359 · pLI 1.00 (gnomAD)
Structure: AlphaFold pLDDT 50.79

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

Similar variants

BBX p.Ala442Thr Benign ★★ same type
BBX p.Ala60= Likely benign ★★ same type
BBX p.Ala892= Benign ★★ same type
BBX p.Ala139Thr Uncertain significance ★ ⚠ same type
BBX p.Ala143Gly Uncertain significance ★ ⚠ same type
BBX p.Ala269Pro Uncertain significance ★ ⚠ same type
BBX p.Ala354Thr Uncertain significance ★ ⚠ same type
BBX p.Ala375Thr 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/bbx-p-arg291cys (accessed [today's date]).

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