Traits

Traits linked to MCCC2

methylcrotonyl-CoA carboxylase subunit 2

The Human Phenotype Ontology links 33 traits to MCCC2, by body system: features seen in people with one of the gene's rare conditions.

Laboratory abnormality

Trait	How often it is seen
Abnormal circulating leucine concentration	Very often (80–99%)
Low blood sugar	Very often (80–99%)
Organic aciduria	Very often (80–99%)
High blood ammonia levels	Often (30–79%)
High blood leucine concentration	Often (30–79%)
Acute hyperammonemia	Not recorded
High urine glycine levels	Not recorded
Ketoacidosis	Not recorded
Ketonuria	Not recorded
Metabolic acidosis	Not recorded
Propionyl-CoA carboxylase deficiency	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Global developmental delay	Always
Abnormality of movement	Often (30–79%)
Cerebral palsy	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Intellectual disability	Sometimes (5–29%)
Coma	Not recorded
Increased reflexes	Not recorded
Lethargy	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Very often (80–99%)
Involuntary muscle stiffness, contraction, or spasm	Sometimes (5–29%)
Generalized decreased muscle tone	Not recorded
Muscle degeneration	Not recorded
Opisthotonus	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Not recorded
Vomiting	Not recorded

Growth abnormality

Trait	How often it is seen
Faltering weight in infancy	Often (30–79%)
Faltering weight	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Carnitine deficiency	Often (30–79%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Abnormality of the cerebral blood vessels	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Seborrheic dermatitis	Not recorded

Abnormality of the integument

Trait	How often it is seen
Hair loss	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory function loss	Sometimes (5–29%)

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to MCCC2 and how often each is seen. Find out more at hpo.jax.org.

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