<prompt> Pancytopenia with cellular marrow is seen in all, except:Megaloblastic anemiaMyelodysplasiaParoxysmal nocturnal hemoglobinuriaG6 PD deficiency  <response>: G6PD deficiency is not associated with pancytopenia and a cellular marrow. So G6PD is the single best answer of choice. Ref: Harrisons Principles of Internal Medicine, 16th Edition, Page 617; Manual of Practical Medicine By R Alagappan, 3rd Edition, Page 335 