A Case of Hereditary Spherocytosis Misdiagnosed as Pyruvate Kinase Deficient Hemolytic Anemia

BACKGROUND: Hereditary spherocytosis (HS) and pyruvate kinase (PK) deficiency are the most common causes of congenital hemolytic anemia. We describe a case of HS with defective PK activity initially misdiagnosed as PK deficiency. METHODS: Hematologic investigation, SDS-PAGE analysis of red cell membrane proteins and sequencing of the PKLR gene were performed. RESULTS: The molecular characterization of the PKLR gene showed a heterozygous mutation 994G > A (Gly332Ser) associated with the promoter substitution -148C > T, whose role in the pathophysiology of PK deficiency is debated. Further investigations revealed spectrin deficiency; the family study demonstrated that the hemolysis was exclusively attributable to HS. CONCLUSIONS: The present case pinpoints to the need for extensive family investigations to correctly diagnose chronic hemolytic anemia, in particular when molecular characterization does not fully explain the clinical phenotype.