This allele was identified in a screen for a metabolic and haematopoietic phenotype described as hypochromic, microcytic anemia associated with erythrocytosis using ENU-treated C57BL/6J males (G0). Sequencing identified a G to T substitution, resulting in a E1121X (changing glutamic acid to a termination codon) mutation in the Ube2o gene. The mutation causes truncation of the C-terminal 168 amino acids and is a loss-of-function mutation. No gene product (protein) is detected by western blot analysis of blood. (J:243727)