In humans, DBA is often diagnosed during the first year of life; common clinical features include anemia, low reticulocyte count, macrocytic erythrocytes (see Box 1 for a glossary of terms), increased expression of fetal hemoglobin and elevated activity of adenosine deaminase (ADA; Box 1) (Fargo et al., 2013; Halperin and Freedman, 1989). Here, ADA is linked to anemia.