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IEMbase 0530: SLC52A3-related Fazio-Londe syndrome

Scope

Field Value
IEMbase ID 530
Nosology 21.3.02.02
Gene SLC52A3
External IDs OMIM:211500; ORPHA:97229
Generated mapping UNMAPPED
Candidate DisMech targets Brown-Vialetto-Van_Laere_Syndrome.yaml#Fazio-Londe spectrum context
Review date 2026-07-07

IEMbase phenotype signal

IEMbase represents SLC52A3-related Fazio-Londe syndrome and notes that it is allelic with Brown-Vialetto-Van Laere syndrome. The record is autosomal recessive, subtype is marked idiopathic, treatability is marked yes, and no treatment rows are listed.

Biochemical rows include normal-to-increased C4-C18 acylcarnitines, low or normal free carnitine, normal-to-increased C6-C10 dicarboxylic acids, ethylmalonic acid, and glutaric acid. Clinical rows emphasize early muscle weakness, respiratory insufficiency from muscle weakness or diaphragm paralysis, and pontobulbar palsy. Sensorineural deafness is absent from this IEMbase record, matching the Fazio-Londe distinction.

DisMech phenotype coverage

The generated UNMAPPED status is a false negative. Brown-Vialetto-Van_Laere_Syndrome.yaml explicitly states that Fazio-Londe disease is now regarded as part of the riboflavin-transporter-deficiency spectrum and is distinguished clinically by bulbar motor neuron disease without prominent deafness.

The local file covers the shared SLC52A3/SLC52A2 riboflavin transporter biology, pontobulbar palsy, respiratory involvement, muscle weakness, and riboflavin treatment rationale. It is broader than the IEMbase Fazio-Londe row because it also covers the deafness-positive BVVL presentation.

Concordance and completeness

Judgement: false negative; use the local Brown-Vialetto-Van Laere syndrome file as the spectrum target, with Fazio-Londe-specific scope noted.

IEMbase is useful for preserving the deafness-absent Fazio-Londe phenotype and for the acylcarnitine/organic-acid prompts. DisMech is stronger for the riboflavin transporter mechanism and treatment rationale.

Curation actions

  • Map this record to Brown-Vialetto-Van_Laere_Syndrome.yaml as Fazio-Londe spectrum context, not as a separate unrelated disease.
  • Preserve the absence of prominent deafness when comparing to the broader BVVL entry.
  • Consider adding Fazio-Londe, OMIM:211500, and SLC52A3 Fazio-Londe aliases to future mapping support.