EOS: The gene for familial eosinophilia. EOS has been mapped to chromosome region 5q31-33 containing the cytokine gene cluster which includes the genes for interleukin-3 (IL-3), interleukin-5 (IL-5), and granulocyte colony-stimulating factor (G-CSF), and all of which are thought play roles in the development, proliferation, and activation of eosinophils.
