Optic nerve hypoplasia/dysplasia in Coffin-Siris syndrome: a case series.

We report 4 patients with Coffin-Siris syndrome (CSS), all exhibiting midline brain abnormalities and all showing either optic nerve hypoplasia or dysplasia. Each of the patients has a unique pathogenic variant in CSS-related genes, including SMARCA4, SMARCB1, SMARCE1, and ARID2, all of which encode components of the BRG1/BRM-associated factor chromatin remodeling complex. The diversity of mutations highlights the molecular heterogeneity of CSS and its potential link to shared developmental pathways affecting the optic nerve.