Transient severe anemia triggered by parvovirus B19 infection in a patient with homozygous RhAG deficiency

Background Deficiency of Rh antigens affects the red blood cell (RBC) membrane integrity, thus reducing erythrocyte survival, clinically manifesting as chronic hemolytic anemia. Various mutations cause such Rh null/mod phenotypes. Parvovirus B19 infection causes transient red cell aplasia, leading to potentially severe anemia in patients with chronic hemolytic disorders. Study Design and Methods A patient with known, etiologically unclear mild chronic anemia presented with a syncopal event. Clinical and laboratory work‐up, including targeted genetic analyses of RBC genes, was performed. Results The patient was severely anemic with moderate signs of hemolysis and evidence of impaired erythropoiesis. Immunohematological work‐up identified a lack of Rh antigen expression. A homozygous c.1034G>A missense mutation in RHAG adequately explains this finding, as well as the chronic hemolysis. Parvovirus B19 was identified as causal for the acute aplastic crisis. Discussion This is the first clinical report of parvovirus B19‐related red cell aplasia in a patient with the RHAG*01M.15 phenotype.