isolated lissencephaly type 1 without known genetic defects
Findings
No curated finding names isolated lissencephaly type 1 without known genetic defects yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Isolated lissencephaly type 1 without known genetic defects belongs to the genetically heterogeneous group, classic lissencephaly. It is a diagnosis of exclusion, when neither associated malformations nor family history are present, and in the absence of mutations of genes known to be involved in classic lissencephaly. Clinically patients present with the common features of classic lissencephaly such as developmental delay, intellectual disability, and seizures.
Definition from the Mondo Disease Ontology (MONDO:0015205), read 2026-09-29. CC BY 4.0.
Features
17 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.
- AgyriaHPOHP:0031882
- Frequent (30% to 79% of cases)
- Axial hypotoniaHPOHP:0008936
- Frequent (30% to 79% of cases)
- EEG with changes in voltageHPOHP:0011201
- Frequent (30% to 79% of cases)
- Enlarged sylvian cisternHPOHP:0100952
- Frequent (30% to 79% of cases)
- Feeding difficultiesHPOHP:0011968
- Frequent (30% to 79% of cases)
- Gray matter heterotopiaHPOHP:0002282
- Frequent (30% to 79% of cases)
- HypsarrhythmiaHPO
Show the remaining 5
- Profound intellectual disabilityHPOHP:0002187
- Frequent (30% to 79% of cases)
- SeizureHPOHP:0001250
- Frequent (30% to 79% of cases)
- Severe intellectual disabilityHPOHP:0010864
- Frequent (30% to 79% of cases)
- SpasticityHPOHP:0001257
- Frequent (30% to 79% of cases)
- VentriculomegalyHPOHP:0002119
- Frequent (30% to 79% of cases)
Where it sits
- A kind of