MCCC2

Chr 5

methylcrotonyl-CoA carboxylase subunit 2

Also known as: MCCB, MCCCbeta

NCBI Gene: 64087 ENSG00000131844 UniProt: Q9HCC0

The protein functions as the small subunit of 3-methylcrotonyl-CoA carboxylase, which catalyzes the carboxylation of 3-methylcrotonyl-CoA to form 3-methylglutaconyl-CoA in leucine catabolism within the mitochondrial matrix. Mutations cause 3-methylcrotonyl-CoA carboxylase 2 deficiency through autosomal recessive inheritance, resulting in impaired leucine breakdown and 3-methylcrotonylglycinuria.

GeneReviews ResearchSummary from RefSeq, OMIM, UniProt, Mechanism

This gene encodes the small subunit of 3-methylcrotonyl-CoA carboxylase. This enzyme functions as a heterodimer and catalyzes the carboxylation of 3-methylcrotonyl-CoA to form 3-methylglutaconyl-CoA. Mutations in this gene are associated with 3-Methylcrotonylglycinuria, an autosomal recessive disorder of leucine catabolism. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, May 2018]

GeneReviews ResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

UniProt3-methylcrotonoyl-CoA carboxylase 2 deficiency

Clinical highlights

Gene-disease validity (ClinGen)

3-methylcrotonyl-CoA carboxylase deficiency · ARDefinitivesufficient evidence for diagnostic panels

Interpreting a novel variant

Loss of function is the curated mechanism (Gene2Phenotype), though the gene is not strongly LoF-constrained in the population — weigh truncating variants against that tolerance.Curated gene-level mechanism — a prior for triage, not a per-variant call.

Active trials

Pubs (1 yr)

—

P/LP submissions

—

P/LP missense

0.90

LOEUF

LOF

Mechanism· G2P

📖

GeneReview available — MCCC2