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IEMbase 0579: SLC18A2-related vesicular monoamine transporter 2 deficiency

Scope

Field Value
IEMbase ID 579
Nosology 23.1.06.01
Gene SLC18A2
External IDs OMIM:193001; ORPHA:352649
Generated mapping UNMAPPED; best candidate Primary_Carnitine_Deficiency.yaml
Candidate DisMech targets None exact
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents SLC18A2-related vesicular monoamine transporter 2 deficiency, also labelled VMAT2 disorder. The record is autosomal recessive, classified under monoamine neurotransmission, flagged as treatable, and lists pramipexole as dopamine-agonist therapy.

Biochemical rows include very high urinary 5-HIAA and HVA, decreased urinary dopamine and norepinephrine, increased CSF 5-HIAA and HVA, decreased blood serotonin, and increased plasma prolactin. Clinical rows include poor head control, hypotonia with extremity hypertonia, dystonia, ataxia, dysarthria, dysdiadochokinesis, hypomimia, hypernasal speech, nasal congestion or profuse nasal secretion, and sweating.

DisMech phenotype coverage

Primary_Carnitine_Deficiency.yaml is a false-positive generated candidate. That entry models SLC22A5/OCTN2 carnitine transport failure, fatty-acid oxidation stress, cardiomyopathy, hypoketotic hypoglycemia, and L-carnitine therapy. It does not represent SLC18A2, VMAT2, vesicular monoamine packaging, or the monoamine metabolite pattern in IEMbase.

The local catecholamine-synthesis material is only broad context for monoamine biology. It does not provide an exact VMAT2 transport subtype.

Concordance and completeness

Judgement: true local gap; reject the primary carnitine deficiency candidate.

The IEMbase record should not be collapsed into carnitine transport or into monoamine synthesis. Its core mechanism is defective vesicular loading of monoamines, with a distinctive biomarker pattern and autonomic/movement-disorder phenotype.

Curation actions

  • Create or identify an exact SLC18A2/VMAT2 deficiency target before import.
  • Reject Primary_Carnitine_Deficiency.yaml as an exact mapping.
  • Preserve the urinary and CSF HVA/5-HIAA, dopamine, norepinephrine, serotonin, prolactin, movement-disorder, and autonomic prompts for later curation.