IEMbase 0666: UQCRC2-related mitochondrial complex III deficiency, nuclear type 5

Scope

Field	Value
IEMbase ID	666
Nosology	7.3.02.01
Nosology code	IEM0457
Gene	UQCRC2
External IDs	OMIM:615160; ORPHA:1460
Generated mapping	CANDIDATE to COX8A-Related_COX_Deficiency.yaml
Candidate DisMech targets	No exact UQCRC2/complex III nuclear type 5 target identified
Review date	2026-07-07

IEMbase phenotype signal

IEMbase represents autosomal recessive UQCRC2-related mitochondrial complex III deficiency, nuclear type 5.

The biochemical and clinical signal is neonatal metabolic disease with increased lactate, increased ammonia, decreased glucose, increased transaminases, hypoglycemia, metabolic acidosis, and possible infantile developmental delay.

DisMech phenotype coverage

No exact UQCRC2 or mitochondrial complex III nuclear type 5 local target was identified.

The generated candidate, COX8A-Related_COX_Deficiency.yaml, is a respiratory chain false positive. It covers COX8A-related cytochrome c oxidase or complex IV deficiency, not UQCRC2-related complex III deficiency. Broad mitochondrial respiratory-chain and Leigh-like disease context may overlap clinically, but the molecular complex and disease target are different.

Concordance and completeness

Judgement: true local gap. The candidate should be rejected as exact coverage.

The IEMbase record is concise but gives a recognizable neonatal mitochondrial energy-failure pattern: lactic acidosis with hypoglycemia, hyperammonemia, transaminase elevation, and developmental delay. That pattern is not enough to map the disease to an unrelated complex IV entry.

Curation actions

• Add a dedicated UQCRC2 / mitochondrial complex III deficiency nuclear type 5 target if this disease is curated.
• Reject COX8A-Related_COX_Deficiency.yaml as the generated target.
• Preserve increased lactate, hypoglycemia, hyperammonemia, metabolic acidosis, increased transaminases, and developmental delay prompts.
• Keep complex III and complex IV deficiency entities distinct.