Donkeys: anemia with decrease ↓ Hb and erythrocyte indices, increase ↑ hematocrit & monocytes; Horses: leukocytosis with altered RBC indices (hemolytic anemia); A. marginale specifically → Horses: ↓ RBCs/monocytes, ↑ WBCs/lymphocytes; Donkeys: ↑ monocytes/hematocrit, ↓ Hb/MCHC. The gene discussed is GSTM1; the disease is anemia.