{
  "id": 19946,
  "label": "hemimegalencephaly",
  "model": {
    "label": "Mondo Disease Ontology (MONDO)",
    "source": 0
  },
  "type_id": 0,
  "reference_id": "MONDO:0020492",
  "properties": {
    "xrefs": [
      "GARD:0002637",
      "ICD9:742.4",
      "MEDGEN:140910",
      "MESH:D065705",
      "NANDO:1200563",
      "NCIT:C177779",
      "NORD:1220",
      "Orphanet:99802",
      "SCTID:253170008",
      "UMLS:C0431391",
      "icd11.foundation:961229160"
    ],
    "synonyms": [
      "unilateral megalencephaly",
      "macrencephaly"
    ],
    "categories": [
      {
        "ref": "MONDO:0005071",
        "name": "nervous system disorder"
      }
    ],
    "definition": "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."
  },
  "isLeaf": true,
  "isRoot": false,
  "child_count": 0,
  "parents": [
    {
      "id": 24020,
      "label": "overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes",
      "isLeaf": false,
      "isRoot": false,
      "parents": [
        19709
      ],
      "type_id": 0,
      "properties": {
        "xrefs": [
          "GARD:0026123"
        ],
        "synonyms": [
          "overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes"
        ],
        "categories": [
          {
            "ref": "MONDO:0005071",
            "name": "nervous system disorder"
          }
        ],
        "definition": "A disease caused by mosaic gain-of-function (GoF) of several genes in the MTOR pathway (MTOR, PIK3CA, PIK3R2 and AKT3) are functionally the same despite significant phenotypic variability. These GoF variants result in overgrowth due to an over-activation of key genes in this pathway. The phenotypic variability is generally attributed to the mosaic fraction and affected tissue types. For example, macrocephaly is noted if the variant is identified in the brain, but non symmetric overgrowth of that limb is noted when the variant is only present in the affected limb. The pathologies of the affected tissue often reveal similar characteristics such as cellular overgrowth. However, this is not always the case especially with focal cortical dysplasia. At times the characteristics pathologies are not present in the tissue but sampling biases are an issue. FCD resections often involve a very small area and so a very small amount of tissue is available for pathology and it is not guaranteed that lesional tissue is sent. Therefore, having a single disease term which can encompass the phenotypic variability yet provide a unifying molecular diagnosis name makes sense given the common functional mechanism."
      },
      "child_count": 5,
      "reference_id": "MONDO:0100283"
    }
  ],
  "children": [],
  "roots": [
    {
      "id": 24020,
      "label": "overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes"
    }
  ]
}