<h4>Background</h4>Coffin-Siris syndrome 12 (CSS12) is a recently described neurodevelopmental disorder caused by heterozygous pathogenic variants in <i>BICRA</i>, a gene encoding a core subunit of the non-canonical BAF (ncBAF) chromatin-remodeling complex. This evidence concerns the gene BANF1 and Coffin-Siris syndrome 12.