Synonyms: 47,XXX syndrome | Triple X syndrome | Triplo-X syndrome | XXX syndrome
Trisomy X is a sex chromosome anomaly with a variable phenotype caused by the presence of an extra X chromosome in females (47,XXX instead of 46,XX).
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 January 2026
Newly diagnosed with
Trisomy X?
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
AXYS
AXYS, the Association for X and Y Chromosome Variations, is an advocacy, education and support organization for individuals with X and Y chromosome variations and their families. This includes those with Klinefelter syndrome (47,XXY), Trisomy X (47,XXX), 47,XYY, 48,XXYY, 48,XXXY and related genetic conditions. The mission of AXYS is to help individuals with one or more extra X and/or Y chromosomes
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
Syndromes Without A Name (SWAN) Australia
Provide information, support and advocacy to families caring for a child with an undiagnosed or rare genetic condition.
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Clinical Trials
For a list of clinical trials in this disease area, please click here.