null syndrome
Findings
No curated finding names null syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
The null syndrome is part of the Pelizaeus-Merzbacher disease (PMD) spectrum and is characterized by mild PMD features associated with demyelinating peripheral neuropathy.
Definition from the Mondo Disease Ontology (MONDO:0017225), read 2026-09-29. CC BY 4.0.
Features
14 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Abnormality of peripheral nerve conductionHPOHP:0003134
- Very frequent (80% to 99% of cases)
- CNS hypomyelinationHPOHP:0003429
- Very frequent (80% to 99% of cases)
- Demyelinating peripheral neuropathyHPOHP:0007108
- Very frequent (80% to 99% of cases)
- Peripheral demyelinationHPOHP:0011096
- Very frequent (80% to 99% of cases)
- AtaxiaHPOHP:0001251
- Frequent (30% to 79% of cases)
- Decreased nerve conduction velocityHPOHP:0000762
- Frequent (30% to 79% of cases)
- Gait disturbanceHPOHP:0001288
- Frequent (30% to 79% of cases)
- Progressive spastic paraplegiaHPOHP:0007020
- Frequent (30% to 79% of cases)
- Abnormal cerebellum morphologyHPOHP:0001317
- Occasional (5% to 29% of cases)
- Inability to walkHPOHP:0002540
- Occasional (5% to 29% of cases)
- Moderate intellectual disabilityHPOHP:0002342
- Occasional (5% to 29% of cases)
- Neurodevelopmental delayHPOHP:0012758
- Occasional (5% to 29% of cases)
Reported absent (1)
- NystagmusHPOHP:0000639
Show the remaining 2
- Optic atrophyHPOHP:0000648
- Occasional (5% to 29% of cases)
- Progressive spastic quadriplegiaHPOHP:0002478
- Occasional (5% to 29% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- PLP1HGNC:9086
- Supportive · Orphanet · X-linked · 2021
Where it sits
Other names
2 names
Resolves to: null syndrome
- Also called
- Pelizaeus-Merzbacher disease, null syndromePLP1 null syndrome