Residual pyruvate kinase activity in PKLR‐deficient erythroid precursors of a patient suffering from severe haemolytic anaemia

• Published in: European journal of haematology 2017-06, Vol.98 (6), p.584-589
• Main Authors: Klei, Thomas R.L., Kheradmand Kia, Sima, Veldthuis, Martijn, Beuger, Boukje M., Geissler, Judy, Dehbozorgian, Javad, Karimi, Mehran, Bruggen, Robin, Zwieten, Rob
• Format: Article
• Language: English
• Subjects: Anemia; Anemia, Hemolytic, Congenital Nonspherocytic - enzymology; Anemia, Hemolytic, Congenital Nonspherocytic - genetics; Anemia, Hemolytic, Congenital Nonspherocytic - pathology; Base Sequence; Blood; Carrier Proteins - genetics; Cell Differentiation; Child; Consanguinity; Erythroblasts; Erythroblasts - enzymology; Erythroblasts - pathology; Erythrocytes; Gene Expression; Glycolysis; Glycolysis - genetics; Hemolytic anemia; Hemopoiesis; Homozygote; Humans; Kinases; Life span; Male; Membrane Proteins - deficiency; Membrane Proteins - genetics; mRNA; Mutation; Myeloid Cells - cytology; Myeloid Cells - enzymology; PKM2; PK‐R; Primary Cell Culture; Pyruvate kinase; Pyruvate Kinase - deficiency; Pyruvate Kinase - genetics; Pyruvate Metabolism, Inborn Errors - enzymology; Pyruvate Metabolism, Inborn Errors - genetics; Pyruvate Metabolism, Inborn Errors - pathology; Pyruvic acid; red blood cell; reticulocyte; Reticulocytes; Reticulocytes - enzymology; Reticulocytes - pathology; RNA, Messenger - genetics; RNA, Messenger - metabolism; Thyroid Hormone-Binding Proteins; Thyroid Hormones - deficiency; Thyroid Hormones - genetics; Western blotting
• ISSN: 0902-4441; 1600-0609
• DOI: 10.1111/ejh.12874

Objective Here, we present a 7‐year‐old patient suffering from severe haemolytic anaemia. The most common cause of chronic hereditary non‐spherocytic haemolytic anaemia is red blood cell pyruvate kinase (PK‐R) deficiency. Because red blood cells rely solely on glycolysis to generate ATP, PK‐R deficiency can severely impact energy supply and cause reduction in red blood cell lifespan. We determined the underlying cause of the anaemia and investigated how erythroid precursors in the patient survive. Methods PK activity assays, Western blot and Sanger sequencing were employed to determine the underlying cause of the anaemia. Patient erythroblasts were cultured and reticulocytes were isolated to determine PK‐R and PKM2 contribution to glycolytic activity during erythrocyte development. Results We found a novel homozygous mutation (c.583G>A) in the PK‐R coding gene (PKLR). Although this mutation did not influence PKLR mRNA production, no PK‐R protein could be detected in the red blood cells nor in its precursors. In spite of the absence of PK‐R, the reticulocytes of the patient exhibited 20% PK activity compared with control. Western blotting revealed that patient erythroid precursors, like controls, express residual PKM2. Conclusions We conclude that PKM2 rescues glycolysis in PK‐R‐deficient erythroid precursors.