H2AC16 (H2A clustered histone 16) is a histone H2A variant encoded on chromosome 6. Based on limited published evidence, H2AC16 belongs to the core histone family and is a structural component of nucleosomes. A germline variant in H2AC16 was identified in one unpublished individual with a rare neurodevelopmental disorder (histonopathy), representing the first known disease association for this gene 1. The clinical features and functional consequences of H2AC16 mutations remain largely uncharacterized.