Prospective screening for δ-hemoglobinopathies associated with decreased hemoglobin A2 levels or hemoglobin A2 variants: A single center experience.

BACKGROUND: δ-hemoglobinopathies may lead to misdiagnosis of several thalassemia syndromes especially ß-thalassaemia carrier, it is important to evaluate the δ-globin gene defects in areas with high prevalence of globin gene disorders. We describe a prospective screening for δ-hemoglobinopathies in a routine setting in Thailand. METHODS: Study was done on a cohort of 8,471 subjects referred for thalassemia screening, 317 (3.7%) were suspected of having δ-globin gene defects due to reduced hemoglobin (Hb) A2 levels and/or appearance of Hb A2-variants on hemoglobin analysis. Hematologic and DNA analysis by PCR and related assays were carried out. RESULTS: DNA analysis of δ-globin gene identified seven different δ-globin mutations in 24 of 317 subjects (7.6%). Both known mutations; δ-77(T>C) (n = 3), δ-68(C>T) (n = 1), δ-44(G>A) (n = 8), Hb A2-Melbourne (n = 5), δIVSII-897(A>C) (n = 5), and Hb A2-Troodos (n = 1) and a novel mutation; the Hb A2-Roi-Et (n = 1) were identified. This Hb A2-Roi-Et, results from a double mutations in-cis, δCD82(AAG>AAT) and δCD133(GTG>ATG), was interestingly found in combination with an in trans, 12.6 kb deletional δß0-thalassemia in an adult Thai woman who had no Hb A2 and elevated Hb F. A multiplex-allele-specific PCR was developed to detect these novel δ-globin gene defects. CONCLUSIONS: The result confirms a diverse heterogeneity of δ-hemoglobinopathies in Thailand which should prove useful in a prevention and control program of thalassemia in the region.

Prenatal prevention for severe thalassemia disease at Srinagarind Hospital.

OBJECTIVE: To evaluate the results and cost-effectiveness of prenatal prevention measurement in severe thalassemia diseases at Srinagarind Hospital. STUDY DESIGN: Descriptive study. SETTING: Antenatal care (ANC) Clinic, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University. SUBJECTS: 1,498 thalassemic screened pregnant women first presenting at ANC Clinic at gestational age less than 17 weeks. MATERIAL AND METHOD: Medical records of thalassemic screened pregnant women between February 2002 and February 2005 were analyzed. Those with a value of mean corpuscular volume (MCV) less than 80 fl, or positive dichlorophenol indophenol precipitation test (KKU-DCIP Clear Reagent Kit) underwent hemoglobin (Hb) typing by high performance liquid chromatography (HPLC) together with thalassemia investigation (complete blood count, MCV and Hb typing) of their husbands and to identify couples at risk of 3 severe thalassemia diseases; Hb Bart's hydrops fetalis, homozygous, -thalassemia and, -thalassemia/ Hb E disease. Then they were advised to undergo DNA analysis and, if they had fetal risk, appropriate prenatal diagnosis was offered. MAIN OUTCOME MEASURE: Number of affected fetuses detected by prenatal diagnosis. RESULTS: Nine hundred and ninety six pregnant women (66.49%) were positive on screening. Of these, 642 (64.46%) had thalassemia investigation done with their spouses. There were 19 couples at risk (1.27% of total screened pregnant women) for having fetal severe thalassemia disease from initial laboratory results. Most of them were, -thalassemia/ Hb E diseases. We found only 10 pregnant women (52.63%) that had undergone prenatal diagnosis. The consequent results were two affected fetuses (20%), one was Hb Bart's hydrops fetalis, and the other was, o-thalassemia/ Hb E disease. In these cases, their parents decided to discontinue the pregnancy. Our prevention program could save 1.14 million bahts for the cost of treatment in two prevented severe thalassemia cases. CONCLUSION: The prenatal prevention program of severe thalassemia disease at Srinagarind Hospital can effectively detect affected fetuses and reduce severe thalassemia disease, which is a major health problem in Thailand.