In contrast, the morphology of mature erythrocytes is significantly altered (Figure 1A) and the percentage of mature Hem1−/− erythrocytes (Stage V) is selectively and significantly decreased indicating that anemia in Hem1−/− mice likely results from the loss of abnormally shaped mature erythrocytes and not from cell intrinsic impairment in erythrocyte development. The gene discussed is NCKAP1L; the disease is anemia (phenotype).