Because human RPS7 mutations are associated with DBA [11], a disease characterized by red cell aplasia, we undertook an initial characterization of circulating blood in adult Rps7Mtu/+ mice (on a C3H/He background) and Rps7Zma/+ mice (on a mixed C57BL/6J; BALB/cJ background). This evidence concerns the gene RPS7 and Pure red cell aplasia.