Mice homozygous for this Irf8 knockout allele (Irf8-/-) may be expected to to exhibit some or all of the phenotype published for other Irf8 null mutations on both a C57BL/6J-congenic and mixed genetic background. For example, other Ifr8 null mice are viable and fertile as young animals. Homozygotes are immunodeficient (abnormal populations of B cells, T cells, granulocytes and macrophages) and develop a syndrome similar to human chronic myeloid leukemia. Acute onset begins by 10 weeks of age, progresses through chronic stage (~20 weeks of age), and significant mortality by ~50 weeks of age. The Jackson Laboratory 2024, used with permission.