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The high prevalence of β-thalassemia in Southeast Asia is a major public health problem. Development of genetic counseling and prenatal diagnosis programs is a priority. To provide the groundwork for such programs in South Vietnam, we determined the spectrum of β-thalassemia mutations in 35 severely affected patients and their relatives. We identified six different β-thalassemia alleles (five β[sup 0] and one β[sup +] mutations), in addition to the common mutation at codon 26 (GAG → AAG) responsible for Hb E. These data provide insights into the distribution of β-thalassemia alleles in the Vietnamese population. [ABSTRACT FROM AUTHOR]

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 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.