Both Cas4 copies display closest sequence similarity to Cas4 homologues from different Clostridia. Furthermore, NitEve‐C1 encodes a HEPN nuclease, a member of an expansive nuclease family that is typically associated with various microbial defence systems, including toxin‐antitoxin, abortive infection, restriction‐modification as well as type III and type VI CRISPR‐Cas systems (Anantharaman et al., 2013; Shmakov et al., 2015). The gene discussed is CASS4; the disease is infection.