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Ring chromosome 20 syndrome

Disease definition

Ring chromosome 20 syndrome is marked by a characteristic seizure phenotype. Depending on the amount of chromosomal loss and associated mosaicism, ring(20) can be associated with macrocephaly, mild to moderate intellectual deficit, or behavioural problems. In rare cases, brain, kidney or heart malformations may be present.


  • Synonym(s):
    • Ring 20
    • Ring chromosome 20
  • Prevalence: <1 / 1 000 000
  • Inheritance: Not applicable or Unknown 
  • Age of onset: Childhood
  • ICD-10: Q93.2
  • OMIM: -
  • UMLS: C0265482  C2930886
  • MeSH: C535369
  • GARD: 1334
  • MedDRA: -
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