Synonyms: Trisomy 21
A total autosomal trisomy that is caused by the presence of a third (partial or total) copy of chromosome 21 and that is characterized by variable intellectual disability muscular hypotonia and joint laxity often associated with a characteristic facial dysmorphism and various anomalies such as cardiac gastrointestinal neurosensorial or endocrine defects.
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 July 2026
Newly diagnosed with
Down syndrome?
Our RARE Concierge Services Guides are available to assist you by providing information, resources and connections as you navigate your rare disease journey.
Advocacy Organizations
Heart of a Giant Foundation
The mission of the HGF is to achieve better health outcomes for heart diseases and related chronic health conditions in our communities and enhance the quality of life through health education, care support, and connection to community resources.
PPP2CA Pathways
PPP2CA Pathways connects families, shares strength, and supports the research community in the search for answers to Houge-Janssens Syndrome type 3.
Pakistan Down Syndrome Association (PDSA)
Vision: Our vision is to ensure that individuals with Down syndrome in Pakistan have equal opportunities, full participation in society, and the support necessary for a fulfilling life. Mission Statement: Empowering individuals with Down syndrome, promoting inclusion, and advocating for their rights and well-being.
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
RareDNA Foundation
Dedicated to improving outcomes for individuals and families affected by rare DNA heart mutations by advancing awareness, access and action. We increase awareness among medical professionals and the public, provide education and resources on diagnosis and treatment, support scientific research, and advocate for faster diagnostic pathways, giving families the knowledge and care they need.
ReNU2 Foundation
ReNU2 Foundation supports families affected by RNU2-2-related neurodevelopmental disease. We foster collaboration, raise awareness, and advance research—pursuing a world where every family has testing, informed care, community, and treatment.
Uganda Alliance of Patients Organization
Supporting patients to access quality, safe and patient-centered healthcare services.
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Clinical Trials
For a list of clinical trials in this disease area, please click here.