The C9 gene (C9 stands for "Complement C9") is a protein coding gene located at chromosome 5p13.1. The C9 gene encodes the last component of the complement system. It is involved in the formation of the"Membrane Attack Complex" (MAC). The MAC -complex attaches to bacterial membranes and forms a pore that allows disruption of bacterial membrane organization.
Mutations in the -C9 gene cause a deficiency of the complement component C9 and thus lead to a dysfunction of the MAC complex .