The other biological tests that may be useful in DBA diagnosis are 1) the erythropoietin (EPO) level, which is consistently elevated in DBA as a result of a lack of effective erythropoiesis with a normal kidney response to the anemia and a quantitative deficiency of the EPO receptors that bind EPO due to the large decreases in the number of erythroid precursors, and 2) immunophenotyping and IgG/IgA agglutinin titer. The gene discussed is EPO; the disease is anemia (phenotype).