Topography of ATF6A and the location of the disease-causing variants identified in patients with ACHM. The diagram depicts the transactivation domain, including the VN8 domain, the bZIP domain and an ERTM domain39. In the C-terminal region, a domain of unknown function that is conserved between ATF6A and ATF6B is also indicated. VN8, eight-residue domain homologous to herpes simplex viral protein VP16 necessary for optimal transcriptional activity and degradation31; bZIP, basic leucine-zipper domain; ERTM,