A Somatic Mutation in the G6PD Gene in Hematopoietic Cells Causes a Chronic Haemolytic Anemia

• Published in: Blood 2009-11, Vol.114 (22), p.4033-4033
• Main Authors: Garçon, Loïc, Tertian, Gérard, Boutron, Audrey, Driss, Françoise, Giraudier, Stéphane, Vainchenker, William, Goossens, Michel, Galacteros, Frederic, Tchernia, Gil, Préhu, Claude
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V114.22.4033.4033

Abstract 4033 Poster Board III-969 G6PD deficiency is the more common human enzyme defect, leading typically to an acute intravascular hemolysis occurring when red cells are exposed to an oxidative stress. However, in rare patients, very low enzymatic level induces the class I G6PD deficiency according to the WHO classification, i.e. a chronic non-spherocytic hemolytic anemia. These cases are all sporadic, occur worldwide, and almost all arise from de novo independent mutations. These mutations are found at the genomic level in both hematopoietic and non hematopoietic cells and occur recurrently in “hot spots”: most of them are located in the exon 10 of the G6PD gene, implicated in the dimer formation and the stability of the active enzyme. No null or frameshift mutations have been reported yet, probably because such mutations would be lethal; indeed, a minimal residual G6PD activity is essential during embryogenesis. We report here the case of 65 years-old Caucasian man referred in 1993 for hemolytic anemia. No personal or familial history of anemia was noted. Nine and five years before, the hemoglobin (Hb) level and the mean corpuscular volume (MCV) were normal. At diagnosis, the anemia was moderate (Hb: 11.9 g/dL), macrocytic (MCV: 104 fL) and regenerative (reticulocyte count: 550G/L) with hemolytic features. Platelets and leucocytes counts were normal. No clinical or ultrasound spleen enlargement was noted. The screening tests ruled out all the classical causes of acquired hemolytic anemia. Red cells half life after Cr51 labelling was shortened with autologous (5 days) but not with allogenous red cells confirming the corpuscular mechanism of the hemolysis. Dosage of erythocyte G6PD activity revealed a very low level (from 0.6 to 1.5 UI/g of Hb, normal range 5.3-7.9). Pyruvate kinase, pyrimidine 5'-nucleotidase and hexokinase enzymatic activities were increased in agreement with the reticulocytosis. With a follow-up of 16 years, evolution was marked by a progressive worsening of the anemia, requiring 8 to 16 packed red cell transfusions per year in parallel with an iron chelation and folic acid therapy. Concomittantly, the macrocytosis increased up to 144 fL. At the molecular level, sequencing of the genomic DNA of the G6PD gene revealed presence of a single nucleotide mutation that altered the IVS 10 nucleotide 1 G>A from donor consensus sequence, leading to an impaired splicing between exon 10 and exon 11. The missplicing creates a premature terminati