IEMbase 0788: AMPD2-related pontocerebellar hypoplasia 9
Scope
| Field | Value |
|---|---|
| IEMbase ID | 788 |
| Nosology | 16.2.05.01 |
| Nosology code | IEM0011 |
| Gene | AMPD2 |
| External IDs | OMIM:615809; OMIM:615686; ORPHA:401805 |
| Generated mapping | CANDIDATE; Pontocerebellar_Hypoplasia.yaml subtype PCH2 |
| Candidate DisMech targets | No exact local AMPD2/PCH9 target |
| Review date | 2026-07-11 |
IEMbase phenotype signal
IEMbase labels this autosomal recessive record as AMPD2-related adenosine monophosphate deaminase deficiency, with alternate name pontocerebellar hypoplasia type 9 (severe) and abbreviation PCH9. The phenotype signal includes microcephaly, seizures, psychomotor delay or retardation, dysmorphic features, midface hypoplasia, broad nasal bridge, short upper lip, and abnormally shaped ears.
DisMech phenotype coverage
Pontocerebellar_Hypoplasia.yaml is a broad PCH entry with several curated
subtypes, including VRK1/PCH1A, EXOSC3/PCH1B, TSEN54/PCH2 and PCH4,
RARS2/PCH6, and CLP1/PCH10. It does not include AMPD2 or PCH9 as a subtype.
Concordance and completeness
Judgement: candidate rejected; true local subtype gap.
The generated PCH2 match is a fuzzy alias match to the PCH series rather than a correct AMPD2/PCH9 match. The broader PCH entry provides useful group context for pontocerebellar hypoplasia, but it cannot be treated as exact coverage for AMPD2-related PCH9.
Curation actions
- Do not accept the generated PCH2 candidate as exact coverage.
- Keep IEMbase 0788 as a local gap unless AMPD2/PCH9 is added to the PCH entry or curated as a separate disease.
- Future curation should preserve AMPD2, PCH9, microcephaly, seizures, psychomotor delay, and the dysmorphic craniofacial prompts.