Anti-C21orf140 antibodies are used in the immunodetection of the protein chromosome 21 open reading frame 140. In humans, the canonical protein has a reported length of 251 amino acid residues and a mass of 29.2 kDa. It is a member of the FAM243 protein family. Synonyms for this target antigen include family with sequence similarity 243 member A, protein FAM243A, and uncharacterized protein C21orf140. C21orf140 gene orthologs have been reported in the mouse, rat, bovine, chimpanzee and chicken species.