Coffin-Siris syndrome

Page most recently updated 7 September 2026

This page focuses on the reported psychiatric associations, which may be the initial presenting manifestation, and on other clinical features that may assist the psychiatrist or primary care physician in identifying the underlying diagnosis, considered through the lenses of the diagnostic lenses framework.

Coffin-Siris syndrome (CSS) is a rare genetic condition affecting multiple organ systems. It is usually inherited in an autosomal dominant manner, although most affected individuals have a de novo genetic change, so absence of a relevant family history does not exclude the diagnosis. A distinctive presentation may include hypoplasia or absence of the fifth fingernails or distal phalanges, and coarse facies.

It can present with psychiatric features such as ADHD, autism spectrum disorder (ASD), hyperactivity, aggression, anxiety, and other behavioural difficulties. Obsessive interests, repetitive behaviours, strong attachment to routines, and unusual fears have also been described, particularly in older children and adolescents.

From a morphologic lens perspective, other features include (but are not limited to):

  • Microcephaly

  • Coarse face

  • Thick vermilion

  • Short palm

  • Small nails

Other characteristic features include developmental delay or intellectual disability, hypotonia, epilepsy, and speech and language difficulties. Other manifestations may include feeding difficulties, sleep disturbance, hearing impairment, ptosis or strabismus, congenital heart defects, genitourinary abnormalities, joint laxity or scoliosis, and frequent infections.

Early diagnosis is important to identify and manage developmental, behavioural, neurological, feeding, respiratory, and other organ-system complications; to provide appropriate developmental, educational, and behavioural support; and to allow surveillance for seizures, sleep disturbance, hearing and vision problems, and other potentially significant complications.

Selected references and further reading — Morphologic lens

Jones KL, Jones MC, del Campo M. Smith's recognizable patterns of human malformation. 8th ed. Philadelphia: Elsevier; 2021.

Reardon W. The bedside dysmorphologist: a guide to identifying and assessing congenital malformations. 2nd ed. Oxford: Oxford University Press; 2016.

Allanson JE, Biesecker LG, Carey JC, Hennekam RCM. Elements of morphology: introduction. Am J Med Genet A. 2009;149A(1):2-5. doi:10.1002/ajmg.a.32601.

Hennekam RCM, Biesecker LG, Allanson JE, Hall JG, Opitz JM, Temple IK, Carey JC; Elements of Morphology Consortium. Elements of morphology: general terms for congenital anomalies. Am J Med Genet A. 2013;161A(11):2726-2733. doi:10.1002/ajmg.a.36249.