Keywords: acquired deficiencies; genetic confirmation; G6PD; pyruvate kinase; red cell enzymopathies EN acquired deficiencies genetic confirmation G6PD pyruvate kinase red cell enzymopathies e45 e48 4 05/10/22 20220515 NES 220515 Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common constitutional erythrocyte enzyme deficiency worldwide, affecting 500 million people. Rare cases of acquired RBC disorders mimicking hereditary forms have been described in haematological diseases [erythropoietic protoporphyria,11 "uroporphyria",12 alpha-thalassaemia myelodysplasia syndrome (ATMDS)].13 These acquired RBC disorders may be misdiagnosed when unexplained manifestations associated with the haematological malignancy are not explored. All the investigations were negative (Table S1; Figure S1) except low G6PD activity (21-3% residual activity) contrasting with an increased PK activity (due to increased level of reticulocyte count; G6PD/PK ratio 0-03; I N i > 0-5). [Extracted from the article]