Is MEF2C p.Pro101= (c.303C>G) pathogenic?

MEF2C p.Pro101= (c.303C>G) is classified Likely benign in MEF2C (ClinVar, Single submitter, 1 submitter; last evaluated 2022-09-06). Very rare (popmax 6.2e-05%); Associated with neurodevelopmental disorder with hypotonia, stereotypic hand movements, and impaired language.

How common is MEF2C p.Pro101= (c.303C>G) in the general population?

MEF2C p.Pro101= (c.303C>G) is very rare (popmax 6.2e-05%) (gnomAD).

MEF2C p.Pro101=

Q: What condition is associated with MEF2C p.Pro101= (c.303C>G)?

MEF2C p.Pro101= (c.303C>G) is associated with neurodevelopmental disorder with hypotonia, stereotypic hand movements, and impaired language (ClinVar).

c.303C>G · rs1777733173 · VCV2028357

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 6.2e-05%)

Conditions

neurodevelopmental disorder with hypotonia, stereotypic hand movements, and impaired language

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP -1.2	GERP -5
Overall
CADD	6.234	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 6.2e-05%

Overall 6.2e-05% 1/1,614,006 alleles · very rare exomes 1/1,461,686 · genomes 0/152,320 · joint denominator

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: MEF2C
Protein: p.Pro101=
Coding: c.303C>G
MANE Select: NM_002397
dbSNP: rs1777733173
Type: single nucleotide variant
Location: chr5:88761284 (GRCh38)
Gene constraint: LOEUF 0.212 · pLI 1.00 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 56.80
Residue 101: the 'disordered' region

Full MEF2C gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

neurodevelopmental disorder with hypotonia, stereotypic hand movements, and impaired language — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

MEF2C p.Pro101Thr Likely pathogenic ★ ⚠ same residue
MEF2C c.638-1G>A Pathogenic/Likely pathogenic ★★ same condition
MEF2C c.638-2A>C Pathogenic ★★ same condition
MEF2C c.965-2A>G Pathogenic ★★ same condition
MEF2C c.-26C>T Pathogenic ★★ same condition
MEF2C c.-8C>T Pathogenic ★★ same condition
MEF2C p.Arg15Cys Pathogenic/Likely pathogenic ★★ same condition
MEF2C p.Arg15His Pathogenic/Likely 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/mef2c-p-pro101 (accessed [today's date]).

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