Is MCCC2 p.Ala218Ser (c.652G>T) pathogenic?

MCCC2 p.Ala218Ser (c.652G>T) is classified Likely pathogenic in MCCC2 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-12-27). AlphaMissense: ambiguous (0.3867); Very rare (popmax 0.00167%, amr); Associated with 3-methylcrotonyl-CoA carboxylase 2 deficiency.

What condition is associated with MCCC2 p.Ala218Ser (c.652G>T)?

MCCC2 p.Ala218Ser (c.652G>T) is associated with 3-methylcrotonyl-CoA carboxylase 2 deficiency (ClinVar).

How common is MCCC2 p.Ala218Ser (c.652G>T) in the general population?

MCCC2 p.Ala218Ser (c.652G>T) is very rare (popmax 0.00167%, amr) (gnomAD).

How is 3-methylcrotonyl-CoA carboxylase deficiency inherited?

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

What do computational predictors say about MCCC2 p.Ala218Ser (c.652G>T)?

AlphaMissense predicts ambiguous (score 0.3867) — an in-silico prediction, not a clinical call.

MCCC2 p.Ala218Ser

c.652G>T · rs886043524 · VCV2092940

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

ambiguous

0.3867 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00167%, amr)

Missense predictors

2/2 damaging

REVEL, SaProt · AlphaMissense no call

Conditions

3-methylcrotonyl-CoA carboxylase 2 deficiency

Computational evidence

Protein change
AlphaMissense	0.3867	ambiguous
REVEL	0.925	moderately pathogenic-leaning
SaProt	LLR -13.81	damaging
⇒ REVEL and SaProt both call this damaging; AlphaMissense makes no call.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 11	GERP 5.1, phastCons 1
Regional constraint	o/e 0.97	unconstrained · MANE · 69 kb · p 0.42 · regional, not allelic
Overall
CADD	27.7	PHRED · no single calibrated threshold — expert panels disagree

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

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00167% Admixed American · 1/60,002 alleles

Filtering AF 0.000124% ClinGen BA1/BS1 input FAF95, joint · FAF99 9e-05%

Overall 0.00041% 6/1,461,826 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.00167%	60,002
European (non-Finnish)	0.000424%	235,997

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: MCCC2
Protein: p.Ala218Ser
Coding: c.652G>T
MANE Select: NM_022132
dbSNP: rs886043524
Type: single nucleotide variant
Location: chr5:71626667 (GRCh38)
Gene constraint: LOEUF 0.832 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 94.82 · 14 PDB
Residue 218: the coa carboxyltransferase n-terminal domain; a UniProt-annotated variant site (in mcc2d); the 'carboxyltransferase' region; a turn

Full MCCC2 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

3-methylcrotonyl-CoA carboxylase 2 deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For 3-methylcrotonyl-CoA carboxylase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages
Prevalence: 1-9 / 100 000 (Europe)

Similar variants

MCCC2 p.Ala218Thr Pathogenic/Likely pathogenic ★★ same residue
MCCC2 p.Ala218Val Likely pathogenic ★★ same residue
MCCC2 c.1000-2A>G Likely pathogenic ★★ same condition
MCCC2 c.1072+1G>A Likely pathogenic ★★ same condition
MCCC2 c.1149+1G>A Pathogenic/Likely pathogenic ★★ same condition
MCCC2 c.1149+1G>T Pathogenic/Likely pathogenic ★★ same condition
MCCC2 c.1216+1G>A Likely pathogenic ★★ same condition
MCCC2 c.1216+2T>A 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/mccc2-p-ala218ser (accessed [today's date]).

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