The main characteristics of Coffin Siris syndrome (CSS), although not present in all patients with a SMARCA4 change, are:
- intellectual disability
- speech delay
- feeding difficulties
- absent or small nail(s) of the fifth finger and/or toe
- excessive hair growth (hypertrichosis)
- certain facial features (e.g. sparse scalp hair, flat nose, large lips).
Other features could be:
- agenesis of the corpus callosum
- frequent infections
- laryngo- or tracheomalacia.