IEMbase 0656: CA5A-related carbonic anhydrase VA deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 656 |
| Nosology | 1.1.09.01 |
| Nosology code | IEM0064 |
| Gene | CA5A |
| External IDs | OMIM:615751; ORPHA:401948 |
| Generated mapping | UNMAPPED; weak candidate Carbamoyl_Phosphate_Synthetase_I_Deficiency.yaml |
| Candidate DisMech targets | No exact local target; broad hyperammonemia/UCD context only |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents autosomal recessive CA5A-related carbonic anhydrase VA deficiency, also labeled hyperammonemia due to carbonic anhydrase VA deficiency.
Clinical rows emphasize neonatal/infantile metabolic decompensation: coma, temperature instability, vomiting, encephalopathy, feeding difficulties, and hypoglycemia. Biochemical rows include increased ammonia, low glucose, normal-to-increased lactate, low-to-normal arginine and citrulline, normal-to-high glutamine, normal urinary orotic acid, and multiple organic acid/acylglycine abnormalities including 3-methylcrotonylglycine, propionylglycine, ketones, 2-ketoglutaric acid, 3-hydroxybutyric acid, 3-hydroxyisovaleric acid, 3-hydroxypropionic acid, adipic acid, fumaric acid, sebacic acid, and suberic acid.
DisMech phenotype coverage
Carbamoyl_Phosphate_Synthetase_I_Deficiency.yaml is a mechanistically related
but gene-specific false exact candidate. It models CPS1 loss at the urea-cycle
entry step, with hyperammonemia, low citrulline, high glutamine, normal/low
orotic acid, encephalopathy, coma, and ammonia neurotoxicity. Those are useful
shared decompensation features, but the file does not model CA5A, mitochondrial
carbonic anhydrase VA, bicarbonate supply to multiple mitochondrial enzymes, or
the IEMbase organic-acid/acylglycine pattern.
No local CA5A or carbonic anhydrase VA deficiency disease entry was found.
Concordance and completeness
Judgement: broad hyperammonemia context only; true CA5A disease-level gap.
The CPS1 entry should not be treated as exact coverage, but it is a useful neighbor for shared acute hyperammonemic encephalopathy. The IEMbase row needs a separate CA5A mechanism to preserve the combined urea-cycle, pyruvate carboxylase, and organic-acid signature.
Curation actions
- Keep this row unmapped until a CA5A target exists.
- Do not map to
Carbamoyl_Phosphate_Synthetase_I_Deficiency.yamlas exact. - Preserve ammonia, glucose, lactate, glutamine, arginine/citrulline, normal orotic acid, organic acids, acylglycines, hypoglycemia, vomiting, encephalopathy, coma, feeding, and temperature-instability prompts.