At that point, his CBC and additional investigations showed mild macrocytic anemia (Hb 9.4 g/dL, MCV 100 fL, references Hb 11.5–14.0 g/dL, MCV 75–85 fL) with a normal reticulocyte count, normal neutrophil and platelet counts, increased fetal hemoglobin (HbF 3.3%) and normal erythrocyte adenosine deaminase activity (eADA 1.0 U/g Hb). This evidence concerns the gene ADA and macrocytic anemia.