Is SDHB p.Ser173Phe (c.518C>T) pathogenic?

SDHB p.Ser173Phe (c.518C>T) is classified Uncertain significance in SDHB (ClinVar, Multiple submitters, 3 submitters; last evaluated 2026-04-02). AlphaMissense: likely pathogenic (0.8734); Very rare (popmax 0.00333%, amr); Associated with pheochromocytoma.

What condition is associated with SDHB p.Ser173Phe (c.518C>T)?

SDHB p.Ser173Phe (c.518C>T) is associated with pheochromocytoma, pheochromocytoma/paraganglioma syndrome 4, gastrointestinal stromal tumor (ClinVar).

How common is SDHB p.Ser173Phe (c.518C>T) in the general population?

SDHB p.Ser173Phe (c.518C>T) is very rare (popmax 0.00333%, amr) (gnomAD).

What do computational predictors say about SDHB p.Ser173Phe (c.518C>T)?

AlphaMissense predicts likely pathogenic (score 0.8734) — an in-silico prediction, not a clinical call.

SDHB p.Ser173Phe

c.518C>T · rs895331139 · VCV1020222

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 3 submitters

AlphaMissense

likely pathogenic

0.8734 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00333%, amr)

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

pheochromocytoma

Computational evidence

Protein change
AlphaMissense	0.8734	likely pathogenic
REVEL	0.901	moderately pathogenic-leaning
SaProt	LLR -15.52	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 12	GERP 2, phastCons 1
Regional constraint	o/e 0.98	unconstrained · MANE · 35 kb · p 0.67 · regional, not allelic
Overall
CADD	32.0	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 0.00333% Admixed American · 2/60,006 alleles

Filtering AF 0.000553% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000207%

Overall 0.000138% 2/1,450,936 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: SDHB
Protein: p.Ser173Phe
Coding: c.518C>T
MANE Select: NM_003000
dbSNP: rs895331139
Type: single nucleotide variant
Location: chr1:17027771 (GRCh38)
Gene constraint: LOEUF 0.741 · pLI 0.03 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 92.14 · 6 PDB
Residue 173: the 'interaction with sdhaf1' region

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

Disease context

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

Also linked: pheochromocytoma/paraganglioma syndrome 4 gastrointestinal stromal tumor hereditary neoplastic syndrome hereditary pheochromocytoma-paraganglioma

Similar variants

SDHB p.Ser173Pro Uncertain significance ★★ ⚠ same residue
SDHB p.Ser173= Benign/Likely benign ★★ same residue
SDHB c.200+1G>A Pathogenic ★★ same condition
SDHB c.200+1G>C Pathogenic/Likely pathogenic ★★ same condition
SDHB c.200+5G>T Likely pathogenic ★★ same condition
SDHB c.201-1G>C Pathogenic/Likely pathogenic ★★ same condition
SDHB c.201-2A>C Pathogenic ★★ same condition
SDHB c.286+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/sdhb-p-ser173phe (accessed [today's date]).

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