Is MCCC2 p.Ala551= (c.1653A>G) pathogenic?

MCCC2 p.Ala551= (c.1653A>G) is classified Uncertain significance in MCCC2 (ClinVar, No assertion criteria, 1 submitter; last evaluated 2020-08-21). Very rare (popmax 0.000508%, nfe); Associated with 3-methylcrotonyl-CoA carboxylase deficiency.

What condition is associated with MCCC2 p.Ala551= (c.1653A>G)?

MCCC2 p.Ala551= (c.1653A>G) is associated with 3-methylcrotonyl-CoA carboxylase deficiency (ClinVar).

How common is MCCC2 p.Ala551= (c.1653A>G) in the general population?

MCCC2 p.Ala551= (c.1653A>G) is very rare (popmax 0.000508%, nfe) (gnomAD).

How is 3-methylcrotonyl-CoA carboxylase deficiency inherited?

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

MCCC2 p.Ala551=

c.1653A>G · rs749529082 · VCV991040

Uncertain significance No assertion criteria

Classification

Uncertain significance

ClinVar

Review

No assertion criteria ☆☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.000508%, nfe)

Conditions

3-methylcrotonyl-CoA carboxylase deficiency

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 -7	GERP -3.1
Overall
CADD	0.053	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000508% European (non-Finnish) · 6/1,179,962 alleles

Filtering AF 0.000183% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00012%

Overall 0.00041% 6/1,461,808 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: MCCC2
Protein: p.Ala551=
Coding: c.1653A>G
MANE Select: NM_022132
dbSNP: rs749529082
Type: single nucleotide variant
Location: chr5:71656821 (GRCh38)
Gene constraint: LOEUF 0.832 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 94.82 · 14 PDB
Residue 551: the coa carboxyltransferase c-terminal domain; the 'carboxyltransferase' region

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

Disease context

3-methylcrotonyl-CoA carboxylase 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.Ala551Thr Uncertain significance ★★ ⚠ same residue
MCCC2 c.1072+1G>A Likely pathogenic ★★ same condition
MCCC2 c.1216+2T>C Likely pathogenic ★★ same condition
MCCC2 p.Ala218Val Likely pathogenic ★★ same condition
MCCC2 p.Ala524Thr Pathogenic/Likely pathogenic ★★ ⚠ same condition
MCCC2 p.Arg155Trp Pathogenic/Likely pathogenic ★★ same condition
MCCC2 p.Arg193Cys Pathogenic/Likely pathogenic ★★ same condition
MCCC2 p.Asn230Asp 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-ala551 (accessed [today's date]).

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