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Tetrasomy X

Disease definition

Tetrasomy X is a sex chromosome anomaly caused by the presence of two extra X chromosomes in females (48,XXXX instead of 46,XX).


Classification level: Disorder
  • Synonym(s):
    • 48,XXXX syndrome
    • Quadruple X
    • Tetra X
  • Prevalence: <1 / 1 000 000
  • Inheritance: -
  • Age of onset: Infancy, Neonatal
  • ICD-10: Q97.1
  • OMIM: -
  • UMLS: C0265496
  • MeSH: C536502
  • GARD: 7754
  • MedDRA: -
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