Toll-like receptor Extended family
 Most mammalian species have between ten and fifteen types of Toll-like receptors. TLRs are not identical in all mammals. For example, a gene coding for a protein like TLR10 in humans is present in mice, but seems to have been damaged at some time by a retrovirus. Other mammals may express TLRs that are not found in humans. Non-mammalian species may have TLRs different from mammals.