Synonyms: Del(21)(q22.11q22.12) | Monosomy 21q22.11q22.12
A rare genetic chromosomal anomaly syndrome resulting from a partial deletion of the long arm of chromosome 21 characterized by pre- and post-natal growth delay short stature intellectual disability developmental delay with severe language impairment thrombocytopenia and craniofacial dysmorphism which may include microcephaly downslanted palpebral fissures low-set ears broad nose thin upper vermillion and downturned corners of the mouth. Brain MRI abnormalities (such as agenesis of the corpus callosum) behavioral problems and seizures may be associated.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version April 2026
Newly diagnosed with
21q22.11q22.12 microdeletion syndrome?
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Advocacy Organizations
Bleeding Disorders Alliance Illinois
The Bleeding Disorders Alliance Illinois exists to improve the quality of life for the inherited bleeding disorders community by supporting individuals and their families with unbiased information and resources which allows them to live healthy and active lives.
Hemophilia Foundation of Southern California
“Improving the quality of life and building community for those living with inherited bleeding disorders in Southern California.”
National Center of Hematology and Blood Transfusion
Treatment of patients with blood diseases,scientific-research works
PPP2CA Pathways
PPP2CA Pathways connects families, shares strength, and supports the research community in the search for answers to Houge-Janssens Syndrome type 3.
Rare Chromosome Disorder Support Group – Unique
Through sharing knowledge and lived experience, Unique helps families and professionals navigate the world of chromosome and gene disorders
Save One Life, Inc
Empowering individuals and families affected by bleeding disorders in developing countries through direct financial assistance and access to medical treatment.
Wave of Support, Inc
Empowering those affected by bleeding disorders and other rare disease through advocacy, resources, education, and support
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Clinical Trials
For a list of clinical trials in this disease area, please click here.