Is POLG p.Pro20Ser (c.58C>T) pathogenic?

POLG p.Pro20Ser (c.58C>T) is classified Uncertain significance in POLG (ClinVar, Single submitter, 1 submitter; last evaluated 2018-05-23). AlphaMissense: likely benign (0.0883); Absent from gnomAD v4.1; Associated with mitochondrial DNA depletion syndrome 4a.

What condition is associated with POLG p.Pro20Ser (c.58C>T)?

POLG p.Pro20Ser (c.58C>T) is associated with mitochondrial DNA depletion syndrome 4a (ClinVar).

How common is POLG p.Pro20Ser (c.58C>T) in the general population?

POLG p.Pro20Ser (c.58C>T) is absent from gnomAD v4.1 (gnomAD).

How is Alpers-Huttenlocher syndrome inherited?

Typically Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

What do computational predictors say about POLG p.Pro20Ser (c.58C>T)?

AlphaMissense predicts likely benign (score 0.0883) — an in-silico prediction, not a clinical call.

POLG p.Pro20Ser

c.58C>T · rs1596362883 · VCV1063425

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.0883 · ACMG-weighted

gnomAD v4.1

Not reported

no allele count reported in gnomAD v4.1 (AN 1,541,538)

Missense predictors

0/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

mitochondrial DNA depletion syndrome 4a

Computational evidence

Protein change
AlphaMissense	0.0883	likely benign
REVEL	0.183	benign-leaning
SaProt	LLR -6.92	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 8	GERP 1.8, phastCons 1
Regional constraint	o/e 1.04	unconstrained · MANE · 13 kb · p 0.21 · regional, not allelic
Overall
CADD	23.0	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean tolerated — 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

No allele count reported in gnomAD v4.1 (AN 1,541,538). This is missing data, not an absence: the variant may or may not be present in gnomAD. Rarity (ACMG PM2) and BA1/BS1 cannot be assessed for it.

Variant & gene context

Gene: POLG
Protein: p.Pro20Ser
Coding: c.58C>T
MANE Select: NM_002693
dbSNP: rs1596362883
Type: single nucleotide variant
Location: chr15:89333697 (GRCh38)
Gene constraint: LOEUF 0.847 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 79.53 · 36 PDB
Residue 20: the 'disordered' region

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

Disease context

mitochondrial DNA depletion syndrome 4a — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Alpers-Huttenlocher syndrome (Orphanet):

Inheritance: Autosomal recessive
Onset: Adolescent, Adult, Childhood, Infancy
Prevalence: 1-9 / 1 000 000 (Europe)

Similar variants

POLG p.Pro20= Likely benign ★★ same residue
POLG c.3643+2T>C Pathogenic ★★★ same condition
POLG p.Ala1105Pro Likely pathogenic ★★★ same condition
POLG p.Arg1096Cys Likely pathogenic ★★★ same condition
POLG p.Asp1184Asn Pathogenic ★★★ same condition
POLG p.Gln1175Ter Likely pathogenic ★★★ same condition
POLG p.Lys1191Asn Likely pathogenic ★★★ same condition
POLG c.3483-14T>C Uncertain significance ★★★ 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/polg-p-pro20ser (accessed [today's date]).

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