IEMbase 0210: FMO3-related primary trimethylaminuria

Scope

Field	Value
IEMbase ID	210
Nosology	2.3.03.01
Gene	FMO3
External IDs	OMIM:602079; ORPHA:468726
Generated mapping	UNMAPPED
Candidate DisMech targets	erythromelalgia.yaml is a false-positive lexical candidate; Dimethylglycine_Dehydrogenase_Deficiency.yaml is only a fish-odor differential
Review date	2026-07-07

IEMbase phenotype signal

IEMbase represents this as FMO3-related flavin-containing monooxygenase 3 deficiency, with alternate labels primary trimethylaminuria, fish odor syndrome, and TMA. Treatability is marked unknown.

The biochemical rows include increased urinary trimethylamine and decreased urinary TMAO/TMA ratio. The characteristic clinical row is fish odor in urine. The additional clinical row states no clinical significance. No treatment rows are listed.

DisMech phenotype coverage

No local DisMech entry covers primary FMO3-related trimethylaminuria. The generated best candidate, erythromelalgia.yaml, is a false-positive match to the word "primary" and has no mechanistic or phenotypic relationship. Dimethylglycine_Dehydrogenase_Deficiency.yaml is also not a target: it includes fish odor as a differential clue but is a DMGDH/dimethylglycine metabolism disorder, not FMO3-dependent trimethylamine oxidation deficiency.

Concordance and completeness

Judgement: true local disease gap.

IEMbase gives a narrow but specific trimethylaminuria profile: FMO3, increased urinary trimethylamine, decreased TMAO/TMA ratio, fish odor, and minimal direct clinical morbidity. DisMech currently lacks the FMO3 entity and should not reuse either erythromelalgia or DMGDH deficiency as a substitute.

Curation actions

• Do not map this record to erythromelalgia.yaml.
• Keep Dimethylglycine_Dehydrogenase_Deficiency.yaml only as a fish-odor differential, not as a trimethylaminuria target.
• Consider a future FMO3/primary trimethylaminuria entry with urinary trimethylamine increase, low TMAO/TMA ratio, fish odor, and low systemic clinical burden.