IEMbase 0043: AASS-related alpha-aminoadipic semialdehyde synthase deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 43 |
| Nosology | 1.8.01.01 |
| Gene | AASS |
| External IDs | OMIM:268700 |
| Generated mapping | UNMAPPED |
| Candidate DisMech targets | None; fuzzy neighbor Succinic_Semialdehyde_Dehydrogenase_Deficiency.yaml |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents this as autosomal recessive AASS-related alpha-aminoadipic semialdehyde synthase deficiency, also named familial hyperlysinemia or saccharopinuria. The cached subtype label is benign form.
The characteristic biochemical pattern is increased lysine in CSF, plasma, and urine, with increased saccharopine in CSF, plasma, and urine. Homocitrulline and N-acetyl-lysine are normal-to-increased in urine. The only clinical statement is no clinical significance in childhood, and IEMbase lists no treatments.
DisMech phenotype coverage
There is no local DisMech entry for primary AASS deficiency, familial hyperlysinemia, or saccharopinuria.
The fuzzy neighbor Succinic_Semialdehyde_Dehydrogenase_Deficiency.yaml is a
false-positive lexical and metabolite-neighbor candidate. It is an ALDH5A1 GABA
catabolism disorder with succinic semialdehyde/GHB accumulation and a
neurologic phenotype, not an AASS lysine degradation disorder.
DECR_Deficiency.yaml also mentions impaired lysine degradation and
hyperlysinemia, but that entry is NADK2-related mitochondrial NADP(H)
deficiency with secondary DECR and lysine-pathway impairment, C10:2
acylcarnitine, and progressive encephalopathy. It is not a disease-level match
for primary AASS deficiency.
Concordance and completeness
Judgement: true unmapped record. No current DisMech disorder captures the primary AASS biochemical disorder.
The most important distinction is primary versus secondary hyperlysinemia. IEMbase ID 43 is a largely benign AASS/saccharopine pathway record. The local DECR entry uses hyperlysinemia as one component of a broader NADK2 mitochondrial disorder, and the SSADH entry is a different aldehyde dehydrogenase/GABA disorder.
Curation actions
- Keep the record unmapped.
- Do not map to SSADH deficiency or DECR deficiency on the basis of semialdehyde or hyperlysinemia wording.
- If curated later, create a standalone AASS/familial hyperlysinemia entry with restrained clinical scope and the lysine/saccharopine biochemical signature.