Monday, February 1, 2021

Coffin-Siris syndrome

Inspired by patients

Curcio MR, Ferranti S, Lotti F, Grosso S. Coffin-Siris syndrome and epilepsy. Neurol Sci. 2021 Feb;42(2):727-729. doi: 10.1007/s10072-020-04782-y. Epub 2020 Oct 2. PMID: 33006724.


Coffin-Siris syndrome is a rare genetic disorder defined by the presence of particular facial traits, congenital malformations, intellectual disability, and speech impairment. Epilepsy in Coffin-Siris syndrome has only occasionally been reported, and its features are poorly defined. We provide a detailed description of the clinical and instrumental findings of three patients with Coffin-Siris syndrome and epilepsy. The clinical diagnosis in our patients was confirmed by molecular analysis, which identified the presence of de novo mutations of ARID1B and SMARCB1 genes, in two patients and one patient, respectively. All the patients presented with epilepsy, with a mean age of seizure onset of 5.5 years. Seizures were brief and had a focal onset with secondary generalization. Electroencephalographic recording documented a unilateral, and less commonly bilateral, paroxysmal activity in the temporal, parietal, and occipital regions. Clinical response to anticonvulsive therapy was satisfactory, with a low rate of seizure recurrence. Our case series contributes to delineate the phenotype of Coffin-Siris syndrome. We wish this report could pave the way for further studies that will better define the prevalence and clinical manifestations of epilepsy in this rare syndrome. 

Kosho T, Okamoto N; Coffin-Siris Syndrome International Collaborators. Genotype-phenotype correlation of Coffin-Siris syndrome caused by mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A. Am J Med Genet C Semin Med Genet. 2014 Sep;166C(3):262-75. doi: 10.1002/ajmg.c.31407. Epub 2014 Aug 28. PMID: 25168959.


Coffin-Siris syndrome (CSS) is a rare congenital malformation syndrome, recently found to be caused by mutations in several genes encoding components of the BAF complex. To date, 109 patients have been reported with their mutations: SMARCB1 (12%), SMARCA4 (11%), SMARCE1 (2%), ARID1A (7%), ARID1B (65%), and PHF6 (2%). We review genotype-phenotype correlation of all previously reported patients with mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A through reassessment of their clinical and molecular findings. Cardinal features of CSS included variable degrees of intellectual disability (ID) predominantly affecting speech, sucking/feeding difficulty, and craniofacial (thick eyebrows, long eyelashes), digital (hypoplastic 5th fingers or toes, hypoplastic 5th fingernails or toenails), and other characteristics (hypertrichosis). In addition, patients with SMARCB1 mutations had severe neurodevelopmental deficits including severe ID, seizures, CNS structural abnormalities, and no expressive words as well as scoliosis. Especially, those with a recurrent mutation "p.Lys364del" represented strikingly similar phenotypes including characteristic facial coarseness. Patients with SMARCA4 mutations had less coarse craniofacial appearances and behavioral abnormalities. Patients with SMARCE1 mutations had a wide spectrum of manifestations from severe to moderate ID. Patients with ARID1A also had a wide spectrum of manifestations from severe ID and serous internal complications that could result in early death to mild ID. Mutations in SMARCB1, SMARCA4, and SMARCE1 are expected to exert dominant-negative or gain-of-function effects, whereas those in ARID1A are expected to exert loss-of-function effects.

Filatova A, Rey LK, Lechler MB, Schaper J, Hempel M, Posmyk R, Szczaluba K, Santen GWE, Wieczorek D, Nuber UA. Mutations in SMARCB1 and in other Coffin-Siris syndrome genes lead to various brain midline defects. Nat Commun. 2019 Jul 4;10(1):2966. doi: 10.1038/s41467-019-10849-y. PMID: 31273213; PMCID: PMC6609698.


Mutations in genes encoding components of BAF (BRG1/BRM-associated factor) chromatin remodeling complexes cause neurodevelopmental disorders and tumors. The mechanisms leading to the development of these two disease entities alone or in combination remain unclear. We generated mice with a heterozygous nervous system-specific partial loss-of-function mutation in a BAF core component gene, Smarcb1. These Smarcb1 mutant mice show various brain midline abnormalities that are also found in individuals with Coffin-Siris syndrome (CSS) caused by SMARCB1, SMARCE1, and ARID1B mutations and in SMARCB1-related intellectual disability (ID) with choroid plexus hyperplasia (CPH). Analyses of the Smarcb1 mutant animals indicate that one prominent midline abnormality, corpus callosum agenesis, is due to midline glia aberrations. Our results establish a novel role of Smarcb1 in the development of the brain midline and have important clinical implications for BAF complex-related ID/neurodevelopmental disorders.


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