Is RB1 p.Ser773Phe (c.2318C>T) pathogenic?

RB1 p.Ser773Phe (c.2318C>T) is classified Uncertain significance in RB1 (ClinVar, Single submitter, 3 submitters; last evaluated 2025-11-09). AlphaMissense: likely pathogenic (0.8273); Very rare (popmax 0.0022%, sas); Associated with retinoblastoma.

What condition is associated with RB1 p.Ser773Phe (c.2318C>T)?

RB1 p.Ser773Phe (c.2318C>T) is associated with retinoblastoma, inherited retinal dystrophy (ClinVar).

How common is RB1 p.Ser773Phe (c.2318C>T) in the general population?

RB1 p.Ser773Phe (c.2318C>T) is very rare (popmax 0.0022%, sas) (gnomAD).

How is Retinoblastoma inherited?

Typically Autosomal dominant, Not applicable (Orphanet). A genetic counselor can assess individual risk for a family.

What do computational predictors say about RB1 p.Ser773Phe (c.2318C>T)?

AlphaMissense predicts likely pathogenic (score 0.8273) — an in-silico prediction, not a clinical call.

RB1 p.Ser773Phe

c.2318C>T · rs267603841 · VCV79393

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 3 submitters

AlphaMissense

likely pathogenic

0.8273 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.0022%, sas)

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

retinoblastoma

Computational evidence

Protein change
AlphaMissense	0.8273	likely pathogenic
REVEL	0.797	moderately pathogenic-leaning
SaProt	LLR -12.22	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.7	GERP 1.5, phastCons 1
Regional constraint	o/e 0.82	unconstrained · MANE · 16 kb · p 0.0046 · regional, not allelic
Overall
CADD	31.0	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean damaging — a triage signal, not a reclassification

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

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0022% South Asian · 2/91,046 alleles

Filtering AF 0.000365% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000137%

Overall 0.000137% 2/1,461,744 alleles · very rare

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: RB1
Protein: p.Ser773Phe
Coding: c.2318C>T
MANE Select: NM_000321
dbSNP: rs267603841
Type: single nucleotide variant
Location: chr13:48465104 (GRCh38)
Gene constraint: LOEUF 0.239 · pLI 1.00 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 77.03 · 19 PDB
Residue 773: a β-strand; the 'interaction with limd1' region; the 'domain c; mediates interaction with e4f1' region

Full RB1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

retinoblastoma — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: inherited retinal dystrophy

For Retinoblastoma (Orphanet):

Inheritance: Autosomal dominant, Not applicable
Onset: Antenatal, Childhood, Infancy
Prevalence: <1 / 1 000 000 (Europe)

Similar variants

RB1 p.Ser773= Likely benign ★★ same residue
RB1 c.1049+1G>A Pathogenic/Likely pathogenic ★★ same condition
RB1 c.1049+1G>T Pathogenic/Likely pathogenic ★★ same condition
RB1 c.1049+3A>G Pathogenic/Likely pathogenic ★★ same condition
RB1 c.1050-2A>G Pathogenic/Likely pathogenic ★★ same condition
RB1 c.1128-1G>A Pathogenic ★★ same condition
RB1 c.1128-2A>G Pathogenic ★★ same condition
RB1 c.1215+1G>A Pathogenic ★★ 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/rb1-p-ser773phe (accessed [today's date]).

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