Is AGRN p.Pro121= (c.363C>G) pathogenic?

AGRN p.Pro121= (c.363C>G) is classified Likely benign in AGRN (ClinVar, Single submitter, 1 submitter; last evaluated 2025-12-22). Very rare (popmax 0.000339%, nfe); Associated with congenital myasthenic syndrome 8.

What condition is associated with AGRN p.Pro121= (c.363C>G)?

AGRN p.Pro121= (c.363C>G) is associated with congenital myasthenic syndrome 8 (ClinVar).

How common is AGRN p.Pro121= (c.363C>G) in the general population?

AGRN p.Pro121= (c.363C>G) is very rare (popmax 0.000339%, nfe) (gnomAD).

AGRN p.Pro121=

c.363C>G · VCV4712328

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.000339%, nfe)

Conditions

congenital myasthenic syndrome 8

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.64	GERP -2.3, phastCons 0.004
Overall
CADD	4.917	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000339% European (non-Finnish) · 4/1,180,004 alleles

Filtering AF 7.9e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 5.4e-05%

Overall 0.000274% 4/1,461,074 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: AGRN
Protein: p.Pro121=
Coding: c.363C>G
MANE Select: NM_198576
Type: single nucleotide variant
Location: chr1:1022362 (GRCh38)
Gene constraint: LOEUF 0.73 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 69.79 · 1 PDB
Residue 121: the nta domain

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

Disease context

congenital myasthenic syndrome 8 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

AGRN p.Pro121His Uncertain significance ★★ same residue
AGRN p.Pro121Ala Uncertain significance ★ same residue
AGRN c.3632-1G>C Likely pathogenic ★★ same condition
AGRN p.Arg1671Ter Pathogenic/Likely pathogenic ★★ same condition
AGRN p.Arg834Ter Pathogenic/Likely pathogenic ★★ same condition
AGRN p.Gly1582Arg Pathogenic ★★ same condition
AGRN p.Gly1675Ser Pathogenic/Likely pathogenic ★★ same condition
AGRN c.1177+4A>G 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/agrn-p-pro121 (accessed [today's date]).

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