In humans, ornithine decarboxylase (ODC) is expressed by the gene ODC1. The protein ODC is sometimes referred to as "ODC1" in research pertaining to humans and mice, but certain species such as Drosophila (dODC2),[3] species of Solanaceae plant family (ODC2),[4] and the lactic acid bacteria Paucilactobacillus wasatchensis (odc2)[5] have been shown to have a second ODC gene.
^Rom E, Kahana C (1993). "Isolation and characterization of the Drosophila ornithine decarboxylase locus: evidence for the presence of two transcribed ODC genes in the Drosophila genome". DNA and Cell Biology. 12 (6): 499–508. doi:10.1089/dna.1993.12.499. PMID8329117.