Synonyms: CSS
A rare genetic syndromic intellectual disability of broad phenotypic range characterized by developmental delay and variable clinical features which most commonly but not consistently include aplasia or hypoplasia of the distal phalanx or nail of the fifth digit and coarse facial features.
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 February 2026
Newly diagnosed with
Coffin-Siris 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
Coffin-Siris Syndrome Foundation
Our mission is to support, connect, and inform the Coffin-Siris Syndrome community, and to promote and fund CSS-related research.
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.