Severe hemolytic anemia in a vietnamese family, associated with novel mutations in the gene encoding for pyruvate kinase

Background and Objectives. Chronic hemolytic anemias are very frequent diseases in intertropical countries mainly caused by hemoglobin disorders. We studied a Vietnamese family in which a first child suffered from a severe transfusion-dependent anemia. The family requested an antenatal diagnosis during a second pregnancy. To characterize the molecular defect, we studied the family over three generations. Design and Methods. Blood from family members was sampled for a full hematologic evaluation, including enzymatic dosage, and DNA analysis was performed for patients displaying pyruvate kinase deficiency (PK-R). Mutation research on the 11 exons of the PKLR gene was done using a scanning method and sequencing. Deletion was evidenced by a Sybergreen((R)) based quantitative real time polymerase chain reaction (PCR) and mapped using quantitative multiplex PCR of short fluorescent fragments spread along the whole sequence of the PKLR gene. Results. Hematologic and molecular studies of this severe chronic anemia demonstrated the existence of two defects in the PKLR gene, a new mutation located on exon 7: c.948C-->G (N316K) and a large deletion extending from exon 4 to exon 10. Interpretation and Conclusions. We describe a family in a South-east Asian country; the proband had severe transfusion-dependent chronic anemia caused by the association between two PKLR gene mutations, PK Saigon (N316K) and PK Viet del 4-10. Severe chronic anemia could be induced by various molecular defects mainly affecting the globin genes. However, even in populations in which hemoglobin diseases are frequent, enzymatic diseases should be considered.