Is ARHGAP20 p.Arg855Cys (c.2563C>T) pathogenic?

ARHGAP20 p.Arg855Cys (c.2563C>T) is classified Likely benign in ARHGAP20 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-06-06). AlphaMissense: likely benign (0.0634); Ultra-rare (popmax 0.0121%, sas).

How common is ARHGAP20 p.Arg855Cys (c.2563C>T) in the general population?

ARHGAP20 p.Arg855Cys (c.2563C>T) is ultra-rare (popmax 0.0121%, sas) (gnomAD).

What do computational predictors say about ARHGAP20 p.Arg855Cys (c.2563C>T)?

AlphaMissense predicts likely benign (score 0.0634) — an in-silico prediction, not a clinical call.

ARHGAP20 p.Arg855Cys

c.2563C>T · VCV3938651

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.0634 · ACMG-weighted

gnomAD v4.1

Rare

ultra-rare (popmax 0.0121%, sas)

Missense predictors

0/3 damaging

AlphaMissense, REVEL, SaProt

Computational evidence

Protein change
AlphaMissense	0.0634	likely benign
REVEL	0.023	moderately benign-leaning
SaProt	LLR -7.63	tolerated
⇒ AlphaMissense, REVEL and SaProt all call this tolerated.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 0.71	GERP -2.1, phastCons 0.22
Regional constraint	o/e 1.01	unconstrained · MANE · 1,589 bp · p 0.87 · regional, not allelic
Overall
CADD	12.55	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 0.0121% South Asian · 11/91,080 alleles

Filtering AF 0.00676% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00522%

Overall 0.00266% 43/1,614,082 alleles · ultra-rare

Ancestry group	Frequency	1 in
South Asiangrpmax	0.0121%	8,280
African / African-American	0.00801%	12,488
Remaining individualsnot grpmax-eligible	0.0032%	31,243
East Asian	0.00223%	44,894
European (non-Finnish)	0.00178%	56,193
Admixed American	0.00167%	60,014
Finnishnot grpmax-eligible	0.00156%	64,022

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: ARHGAP20
Protein: p.Arg855Cys
Coding: c.2563C>T
MANE Select: NM_001384657
Type: single nucleotide variant
Location: chr11:110580383 (GRCh38)
Gene constraint: LOEUF 0.613 · pLI 0.07 (gnomAD)
Structure: AlphaFold pLDDT 55.05 · 1 PDB

Full ARHGAP20 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Similar variants

ARHGAP20 p.Arg855His Uncertain significance ★ ⚠ same residue
ARHGAP20 p.Arg855Leu Uncertain significance ★ ⚠ same residue
ARHGAP20 p.Arg855Pro Uncertain significance ★ ⚠ same residue
ARHGAP20 p.Ala1056Gly Uncertain significance ★ ⚠ same type
ARHGAP20 p.Ala1077Gly Uncertain significance ★ ⚠ same type
ARHGAP20 p.Ala202Thr Uncertain significance ★ ⚠ same type
ARHGAP20 p.Ala222Val Uncertain significance ★ ⚠ same type
ARHGAP20 p.Ala316Thr 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/arhgap20-p-arg855cys (accessed [today's date]).

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