Search for a rare disease

* (*) mandatory field

Other search option(s)

Suggest an update

(*) Required fields.


Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Captcha image

Ring chromosome 21 syndrome

Disease definition

Ring chromosome 21 syndrome is an autosomal anomaly characterized by variable clinical features, most commonly including growth retardation, developmental delay, intellectual disability, epilepsy, microcephaly, short stature, dysmorphic features, hypogammaglobulinemia, thrombocytopenia and unspecific skeletal anomalies (hemivertebrae, clinodactyly, syndactyly). In rare cases, it has been described in phenotypically normal individuals.


  • Synonym(s):
    • Chromosome 21 en anneau
    • Ring 21
    • Ring chromosome 21
  • Prevalence: Unknown
  • Inheritance: -
  • Age of onset: Antenatal, Neonatal
  • ICD-10: Q93.2
  • OMIM: -
  • UMLS: C0265487  C2931422
  • MeSH: C537109
  • GARD: 6083
  • MedDRA: -

Additional information

Specialised Social Services

The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.