Hemimegalencephaly
Synonyms: Unilateral megalencephaly
- Type
- Malformation syndrome
- Group
- Disorder
- Inheritance
- Not applicable
- Age of onset
- Infancy
- Status
- active
Hemimegalencephaly is a rare cerebral malformation characterized by overgrowth of all or part of a cerebral hemisphere, often with ipsilateral severe cortical dysplasia or dysgenesis, white matter hypertrophy and dilated lateral ventricle, presenting in early infancy with progressive hemiparesis, severe psychomotor retardation and intractable seizures. Hemimegalencephaly may be an isolated finding or associated with other syndromes such as angioosteohypertrophic syndrome, epidermal nevus syndrome and Ito hypomelanosis. Management includes seizure control by antiepileptic medications and early hemispherectomy.
Names in Orphadata languages
12 of 12 languages| Lang | Name | Synonyms |
|---|---|---|
| en | Hemimegalencephaly | Unilateral megalencephaly |
| fr | Hémimégalencéphalie | Mégalencéphalie unilatérale |
| de | Hemimegalenzephalie | Megalenzephalie, unilaterale |
| es | Hemimegalencefalia | Megalencefalia unilateral |
| it | Emimegalencefalia | Megalencefalia monolaterale |
| nl | Hemimegalencefalie | Unilaterale megalencefalie |
| pt | Megalencefalia unilateral | |
| pl | Hemimegaencefalia | Megaencefalia jednostronna |
| cs | Hemimegalencefalie | Unilaterální megalencefalie |
| uk | Гемімегаленцефалія | Одностороння мегаленцефалія |
| zh | 半侧巨脑畸形 | 单侧巨脑畸形 |
| tr | Hemimegalensefali | Unilateral megalensefali |
Definition in:
Cross-references
qualifier = Orphanet mapping relation| Source | Code | Qualifier | ICD relation | Validation |
|---|---|---|---|---|
| ICD-10 | Q04.5 | NTBT | attributed | validated |
| ICD-11 | LA05.1 | NTBT | index | validated |
| MONDO | 0020492 | E | validated | |
| MeSH | D065705 | E | validated | |
| UMLS | C0431391 | E | validated | |
| GARD | 2637 | E | validated | |
| MedDRA | 10078100 | E | validated |
E exact · NTBT this ORPHAcode is narrower than the target · BTNT broader than the target · ND not decided.
Classification
Preferential parent (Orphanet linearisation):
Parents in the classifications (3):
- ORPHA:166478Cerebral malformation with epilepsy
rare genetic diseases; rare neurological diseases - ORPHA:199633Non-syndromic cerebral malformation
rare developmental anomalies during embryogenesis; rare neurological diseases - ORPHA:530313PIK3CA-related overgrowth spectrum disorder
rare developmental anomalies during embryogenesis; rare genetic diseases
No children.
Genes
3 direct| Gene | Association | Status | HGNC | Ensembl | OMIM | Locus | Name | Source of validation |
|---|---|---|---|---|---|---|---|---|
| AKT3 | Disease-causing somatic mutation(s) in | Assessed | HGNC:393 | ENSG00000117020 | 611223 | 1q43-q44 | AKT serine/threonine kinase 3 | 22500628[PMID] |
| MTOR | Disease-causing somatic mutation(s) in | Assessed | HGNC:3942 | ENSG00000198793 | 601231 | 1p36.22 | mechanistic target of rapamycin kinase | 32140648[PMID] |
| PIK3CA | Disease-causing somatic mutation(s) in | Assessed | HGNC:8975 | ENSG00000121879 | 171834 | 3q26.32 | phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha | 22729223[PMID] |
Prevalence and incidence
1 record| Type | Class | Value | Area | Qualification | Validation | Source |
|---|---|---|---|---|---|---|
| Point prevalence | Unknown | — | Worldwide | Class only | Validated | ORPHANET |
Value is Orphadata's ValMoy: the mean estimate per 100 000 for prevalence and incidence, the number of cases or families for case reports.
HPO phenotypes
33 annotations · validated 2021-03-11| HPO | Term (as annotated by Orphanet) | Diagnostic |
|---|---|---|
| Very frequent (99-80%) | ||
| HP:0030890 | Hyperintensity of cerebral white matter on MRI | |
| HP:0025373 | Interictal EEG abnormality | |
| HP:0001250 | Seizure | |
| Frequent (79-30%) | ||
| HP:0000929 | Abnormal skull morphology | |
| HP:0000267 | Cranial asymmetry | |
| HP:0010851 | EEG with burst suppression | |
| HP:0011195 | EEG with focal sharp slow waves | |
| HP:0011193 | EEG with focal spikes | |
| HP:0002392 | EEG with polyspike wave complexes | |
| HP:0032046 | Focal cortical dysplasia | |
| HP:0011153 | Focal motor seizure | |
| HP:0001263 | Global developmental delay | |
| HP:0011215 | Hemihypsarrhythmia | |
| HP:0007206 | Hemimegalencephaly | |
| HP:0002126 | Polymicrogyria | |
| HP:0002119 | Ventriculomegaly | |
| Occasional (29-5%) | ||
| HP:0012757 | Abnormal neuron morphology | |
| HP:0010819 | Atonic seizure | |
| HP:0006824 | Cranial nerve paralysis | |
| HP:0011097 | Epileptic spasm | |
| HP:0011167 | Focal tonic seizure | |
| HP:0004302 | Functional motor deficit | |
| HP:0002171 | Gliosis | |
| HP:0002282 | Gray matter heterotopia | |
| HP:0012377 | Hemianopia | |
| HP:0001269 | Hemiparesis | |
| HP:0010864 | Intellectual disability, severe | |
| HP:0000256 | Macrocephaly | |
| HP:0001336 | Myoclonus | |
| HP:0012246 | Oculomotor nerve palsy | |
| HP:0000648 | Optic atrophy | |
| HP:0001302 | Pachygyria | |
| HP:0002133 | Status epilepticus | |
Run the differential on the 3 obligate / very frequent terms
Annotation source: 25296542[PMID]_16821075[PMID]_30677308[PMID]
Sources for this card
- Orphanet page: orpha.net/en/disease/detail/99802
- This record as JSON: /data/d/99802.json