Coffin-Siris and Nicolaides-Baraitser syndromes are a common well recognizable cause of intellectual disability

Brain Dev. 2015 May;37(5):527-36. doi: 10.1016/j.braindev.2014.08.009. Epub 2014 Sep 22.


Background: Nicolaides-Baraitser and Coffin-Siris syndromes are emerging conditions with overlapping clinical features including intellectual disability and typical somatic characteristics, especially sparse hair, low frontal hairline, large mouth with thick and everted lips, and hands and feet anomalies. Since 2012, mutations in genes encoding six proteins of the BAF complex were identified in both conditions.

Methods and results: We have clinically evaluated a cohort of 1161 patients with intellectual disability from three different Italian centers. A strong clinical suspicion of either Nicolaides-Baraitser syndrome or Coffin-Siris syndrome was proposed in 11 cases who were then molecularly confirmed: 8 having de novo missense mutations in SMARCA2, two frame-shift mutations in ARID1B and one missense mutation in SMARCB1. Given the high frequency of the condition we set up a one-step deep sequencing test for all 6 genes of the BAF complex.

Conclusions: These results prove that the frequency of these conditions may be as high as the most common syndromes with intellectual deficit (about 1%). Clinical geneticists should be well aware of this group of disorders in the clinical setting when ascertaining patients with intellectual deficit, the specific facial features being the major diagnostic handle. Finally, this work adds information on the clinical differences of the two conditions and presents a fast and sensitive test for the molecular diagnosis.

Keywords: ARID1B; BAF-complex; Coffin–Siris syndrome; Nicolaides–Baraitser syndrome; SMARCA2; SMARCB1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abnormalities, Multiple / genetics*
  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Chromosomal Proteins, Non-Histone / genetics
  • Cohort Studies
  • DNA-Binding Proteins / genetics
  • Face / abnormalities*
  • Facies
  • Female
  • Foot Deformities, Congenital / complications
  • Foot Deformities, Congenital / genetics
  • Genetic Association Studies
  • Hand Deformities, Congenital / complications
  • Hand Deformities, Congenital / genetics*
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Hypotrichosis / complications
  • Hypotrichosis / genetics
  • Infant
  • Intellectual Disability / complications
  • Intellectual Disability / etiology*
  • Intellectual Disability / genetics
  • Male
  • Micrognathism / complications
  • Micrognathism / genetics*
  • Neck / abnormalities*
  • SMARCB1 Protein
  • Transcription Factors / genetics


  • ARID1B protein, human
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • SMARCA2 protein, human
  • SMARCB1 Protein
  • SMARCB1 protein, human
  • SWI-SNF-B chromatin-remodeling complex
  • Transcription Factors

Supplementary concepts

  • Coffin-Siris syndrome
  • Nicolaides Baraitser syndrome