Coffin-Siris syndrome (CSS) is an uncommon congenital disease that affects many systems in the body. It presents with a wide range of clinical features.

CSS can be caused by heterozygous genetic mutations in any of the genes that have been linked to the condition. Examples include the genes ARID1B (AT-rich interactive domain-containing protein 1B), and SMARCA4 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4) [1]. Although some mutations are inherited (according to an autosomal dominant pattern), many cases of CSS occur de novo [2].

Regularly reported features include intellectual and developmental impairment with varying severity, dysmorphic facial features, and dysplastic nails on the fifth digit. These are considered the major features of CSS. Typical CSS facies exhibit a wide mouth and nasal bridge, everted lips, downward slanting eyes, and thick eyebrows. The more frequently observed minor features of CSS include failure to thrive, short stature, microcephaly, and sparse scalp hair. In contrast, there may be excessive hair growth, usually involving the torso, face and upper limbs.

In the central nervous system (CNS), manifestations of CSS include seizures, Dandy-Walker malformation, hypotonia, and other anatomical abnormalities. Furthermore, patients diagnosed with CSS are also prone to abnormalities in other systems, such as the cardiovascular system (CVS). A few of the known CVS manifestations are exemplified by tetralogy of Fallot (ToF), atrial septal defect (ASD) or ventricular septal defect (VSD) [3]. CSS may cause hearing problems, as well as visual impairment. Ocular abnormalities include cataracts and strabismus.
Various other minor features have been described, such as single palmar creases, low set ears, renal malformations, and gastrointestinal and skeletal abnormalities [4] [5]. The latter may appear as spinal abnormalities such as scoliosis, often seen during childhood.

Individuals affected by CSS have a higher incidence of infections, compared with the general population, due to a higher susceptibility. Infections can occur in numerous parts of the body, including the respiratory and urogenital systems [5] [6].

Coffin-Siris syndrome may be diagnosed clinically through the assessment of presenting signs and symptoms. Although the type of feature presenting, whether major or minor, is important when considering the diagnosis of CCS, there is no set of standard diagnostic criteria for the condition [7]. Hypoplasia or aplasia of the fifth digit nail and distal phalanx may be absent, and is not necessary for the diagnosis of CSS to be made. Genetic testing is used to confirm the diagnosis; however, prenatal detection of the condition is limited by the presence of spontaneous cases [2].

There is no cure for Coffin-Siris Syndrome 2, so treatment focuses on managing symptoms and improving quality of life. A multidisciplinary approach is often necessary, involving physical therapy to improve motor skills, speech therapy to address communication challenges, and occupational therapy to enhance daily living skills. Educational support and individualized learning plans can help address intellectual disabilities. Regular follow-ups with healthcare providers are important to monitor progress and adjust treatments as needed.

The prognosis for individuals with CSS2 varies depending on the severity of symptoms and the presence of any associated health issues. While intellectual and developmental challenges are common, many individuals can lead fulfilling lives with appropriate support and interventions. Early diagnosis and intervention can significantly improve outcomes by addressing developmental delays and other symptoms promptly.

Coffin-Siris Syndrome 2 is caused by mutations in the ARID1B gene, which plays a crucial role in chromatin remodeling. This process is essential for regulating gene expression and ensuring proper development. Mutations in ARID1B disrupt normal gene function, leading to the characteristic features of CSS2. The condition is typically inherited in an autosomal dominant pattern, meaning a single copy of the mutated gene can cause the disorder.

CSS2 is a rare condition, with only a few hundred cases reported in the medical literature. It affects both males and females equally and has been identified in various ethnic groups worldwide. Due to its rarity and the variability of symptoms, CSS2 may be underdiagnosed or misdiagnosed as other developmental disorders.

The pathophysiology of Coffin-Siris Syndrome 2 involves disruptions in chromatin remodeling due to ARID1B gene mutations. Chromatin remodeling is a process that alters the structure of chromatin, the complex of DNA and proteins in the cell nucleus, to regulate gene expression. Disruptions in this process can lead to abnormal development and the diverse symptoms seen in CSS2, affecting multiple systems in the body.

Currently, there are no known methods to prevent Coffin-Siris Syndrome 2, as it is a genetic disorder. Genetic counseling may be beneficial for families with a history of CSS2 or related conditions, providing information about the risks of recurrence in future pregnancies and discussing reproductive options.

Coffin-Siris Syndrome 2 is a rare genetic disorder caused by mutations in the ARID1B gene, leading to developmental delays, intellectual disabilities, and distinctive facial features. Diagnosis involves clinical evaluation and genetic testing, while treatment focuses on managing symptoms through a multidisciplinary approach. Although there is no cure, early intervention can improve outcomes. Understanding the genetic basis and pathophysiology of CSS2 is crucial for developing future therapies and support strategies.

For patients and families affected by Coffin-Siris Syndrome 2, understanding the condition is essential. CSS2 is a genetic disorder that affects development and can cause a range of symptoms, including learning difficulties and unique facial features. While there is no cure, therapies and educational support can help manage symptoms and improve quality of life. Genetic counseling can provide valuable information for families considering future pregnancies. Regular medical follow-ups and a supportive care team are important for addressing the needs of individuals with CSS2.

1. Wieczorek D, Bögershausen N, Beleggia F, et al. A comprehensive molecular study on Coffin-Siris and Nicolaides-Baraitser syndromes identifies a broad molecular and clinical spectrum converging on altered chromatin remodeling. Hum Mol Genet. 2013;22(25):5121-5135.
2. Vergano SS, Santen G, Wieczorek D, Wollnik B, Matsumoto N, Deardorff MA. Coffin-Siris Syndrome. GeneReviews. http://www.ncbi.nlm.nih.gov/books/NBK131811/. Published July 11, 2013. Accessed June 21, 2018.
3. Vergano SS, Deardorff MA. Clinical features, diagnostic criteria, and management of Coffin-Siris syndrome. Am J Med Genet C Semin Med Genet. 2014;166C(3):252-256.
4. Hoyer J, Ekici AB, Endele S, et al. Haploinsufficiency of ARID1B, a member of the SWI/SNF-a chromatin-remodeling complex, is a frequent cause of intellectual disability. Am J Hum Genet. 2012;90(3):565-572.
5. Tsurusaki Y, Okamoto N, Ohashi H, et al. Mutations affecting components of the SWI/SNF complex cause Coffin-Siris syndrome. Nat Genet. 2012;44(4):376-378.
6. Kellermayer R, Kitagawa S, Redel CA, Cass DL, Belmont JW, Klish W. Upper gastrointestinal malformations in Coffin-Siris syndrome. Am J Med Genet A. 2007;143A(13):1519-1521.
7. Fleck BJ, Pandya A, Vanner L, Kerkering K, Bodurtha J. Coffin-Siris syndrome: review and presentation of new cases from a questionnaire study. Am J Med Genet. 2001;99(1):1-7.