We investigated disseminated neoplasia found in M. chilensis from Argentina and Chile, as well as M. edulis from France and the Netherlands, to determine if these cancers are transmissible cancers or conventional cancers and, if transmissible, whether these cancers represent new cases of the same lineage of transmissible cancer previously reported in Canada (here termed Mytilus BTN1) or whether they are novel cancer lineages. This evidence concerns the gene BTN1A1 and neoplasm.