IEMbase 0005: QDPR-related dihydropteridine reductase deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 5 |
| Nosology | 21.1.05.01 |
| Gene | QDPR |
| External IDs | OMIM:261630 |
| Generated mapping | MAPPED by alias_exact:dihydropteridine reductase deficiency |
| DisMech target | kb/disorders/Tetrahydrobiopterin_Deficiency.yaml#DHPR Deficiency |
| Review date | 2026-07-07 |
IEMbase phenotype signal
Characteristic clinical features include axial hypotonia, basal ganglia calcifications on CT, intellectual disability, and myoclonic seizures. Additional features include choreoathetosis, cortical/subcortical atrophy, drooling, abnormal EEG with generalized slowing or spike-wave discharges, hypopigmented hair, microcephaly, pneumonia, psychomotor delay, eczematous rash, tonic-clonic seizures, sudden death, and temperature instability.
The biochemical pattern includes increased phenylalanine, low CSF 5-HIAA and homovanillic acid, low DHPR activity in dried blood spots, BH4 loading response, increased biopterin and BH2, generally normal neopterin, and increased prolactin.
Treatments listed are sapropterin/BH4, phenylalanine-reduced diet, levodopa/carbidopa, 5-hydroxytryptophan, and folinic acid.
DisMech phenotype coverage
DisMech correctly maps this to the DHPR subtype of Tetrahydrobiopterin
Deficiency. The local umbrella captures the major shared phenotype set:
hyperphenylalaninemia, developmental delay, intellectual disability, hypotonia,
dystonia/parkinsonism, oculogyric crisis, seizures, hyperprolactinemia, CSF
neurotransmitter metabolites, pterin profiling, and the expected therapies
including folinic acid.
Concordance and completeness
Judgement: correct mapping with moderate-to-high concordance.
IEMbase is richer for subtype-specific diagnostic detail. DisMech does not currently expose DHPR activity, BH2 elevation, neopterin-normal pattern, basal ganglia calcification, EEG abnormalities, or brain atrophy as explicit subtype-level findings.
Curation actions
- Keep the mapping.
- Consider DHPR-specific biochemical entries for dried-blood-spot DHPR activity, BH2 elevation, and pterin-pattern interpretation.
- Consider basal ganglia calcification and EEG abnormalities if supported by accepted sources.