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.

Orphanet doesn't provide personalised answers. To get in touch with the Orphanet team, please contact

Information provided in your contribution (including your email address) will be stocked in .CSV files that will be sent as an email to Orphanet's teams. These emails might be conserved in the teams' mailboxes, in our backoffice servers but will not be registered in our databases (for more information see our section General Data Protection Regulation and data privacy (GDPR) and Confidentiality).

Captcha image

9q33.3q34.11 microdeletion syndrome

Disease definition

Partial monosomy of the long arm of chromosome 9 characterized by intellectual disability, developmental delay with pronounced speech delay, short stature, and muscular hypotonia. Common craniofacial dysmorphic features consist of microcephaly, prominent forehead, round face, arched eyebrows, upslanting palpebral fissures, strabismus, short nose, and thin upper lip. Other clinical findings include epilepsy, ataxia, unspecific brain MRI findings, early-onset primary dystonia, nail dysplasia, and bone malformations, in particular patellar abnormalities, epistaxis, and cutaneous-mucous telangiectasias.


Classification level: Disorder
  • Synonym(s):
    • Del(9)(q33.3q34.11)
    • Deletion 9q33.3q34.11
    • Monosomy 9q33.3q34.11
  • Prevalence: <1 / 1 000 000
  • Inheritance: -
  • Age of onset: Infancy, Childhood
  • ICD-10: -
  • OMIM: -
  • UMLS: -
  • MeSH: -
  • GARD: -
  • MedDRA: -

Detailed information

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.