Thalassemia and hemoglobinopathies rather than iron deficiency are major causes of pregnancy-related anemia in northeast Thailand

A cross-sectional prevalence study of anemia was undertaken on 412 pregnant women in northeast Thailand during January 2003 to May 2004. With standardized diagnostic protocols and the CDC criteria of anemia [hemoglobin (Hb) < 11 g/dl at < or = 12 weeks of gestation and Hb < 10.5 g/dl at < or = 20 weeks of gestation], 71 (17.2%) subjects were anemic. Of these, 42 (59.2%) subjects had thalassemia, 5 (7.0%) had iron deficiency, 18 (25.4%) had combined thalassemia and iron deficiency and 6 (8.5%) had no thalassemia nor iron deficiency. Adjusted logistic regression analyses indicated that various thalassemia genotypes were significantly related to anemia, while homozygous Hb E had the highest risk with an odds ratio (OR) of 44.8 (95% CI 12.6-159.7). In comparison, iron deficiency demonstrated a much lower risk with OR of 3.1 (95% CI 1.4-6.8). This finding suggests that the contribution of iron deficiency to pregnancy associated anemia in this region is low.     

Compound heterozygote states for Hb C/Hb Malay and Hb C/Hb E in pregnancy: a molecular and hematological analysis

Hemoglobin (Hb) C (alpha2beta(2)6Glu-Lys) is a variant Hb found mainly in West Africa where individuals carrying both Hb C and Hb S (alpha2beta(2)6Glu-Val) usually have a disease similar to sickle cell disease. The Hb C molecule has reduced solubility leading to crystal formation and hemolytic anemia. We report a hitherto undescribed interaction of Hb C and Hb Malay (alpha2beta(2)19Asn-Ser) in a Thai individual. She was a 24-year-old pregnant woman with moderate anemia who had the following hematologic data; Hb 8.9 g/dl, Hct 30.0%, MCV 81.0 fl, MCH 24.1 pg, MCHC 29.7 g/dl, RDW 17.1% and instead of Hb crystal a marked number of target cell in peripheral blood was observed. Hb analysis revealed 22.5% Hb Malay, 64.6% Hb C and 4.5% Hb A2. Globin gene analyses demonstrated that she carried the betaC mutation (beta6: GAG-AAG) in trans to the betaMalay mutation (beta19: AAC-AGC). Hematologic data of the patient were compared to those of the compound heterozygote for Hb C and Hb E (alpha2beta(2)26Glu-Lys) found in 5 other unrelated Thai pregnant women and 11 pregnant women with Hb C heterozygote with or without co-inheritance of alpha-thalassemia who had much lower Hb C levels and the non-pregnant women with Hb C heterozygote and a compound Hb E/Hb Malay syndrome. Different genotype-phenotype correlations observed in these Thai patients with Hb C disorders are illustrated.     

Phenotypic expression of hemoglobins A₂, E and F in various hemoglobin E related disorders

Study on the phenotypic expression of hemoglobin (Hb) A(2) and Hb E in Hb E disorders has been difficult due to the co-separation of Hb A(2) and Hb E in most Hb analysis assays. Because these two Hbs are separated on capillary electrophoresis, we studied phenotypic expression of Hbs A(2), E and F in various Hb E disorders using this system. This was done on 362 subjects with several Hb E disorders including heterozygous Hb E, homozygous Hb E, β-thalassemia/Hb E, δβ-thalassemia/Hb E, and Hb Lepore/Hb E and those of these disorders with several forms of α-thalassemia. Normal controls showed Hb A(2) of 2.7 ± 0.3%. Heterozygous Hb E and homozygous Hb E had elevated Hb A(2) i.e. 3.8 ± 0.3% and 4.8 ± 0.5%, respectively. Further elevations were observed for β(0)-thalassemia/Hb E (6.1 ± 1.9%) and β(+)-thalassemia/Hb E (7.1 ± 1.2%). Interestingly, no elevation of Hb A(2) was found in the δβ-thalassemia/Hb E, and Hb Lepore/Hb E (2.3 ± 0.3%) but higher Hb F levels were noted which could be useful diagnostic markers. The levels of Hb E were variable. Co-inheritance of these Hb E disorders with α-thalassemia were associated with lower outputs of Hb E and Hb F but the levels of Hb A(2) were not altered. Different phenotypic expression of Hb A(2), Hb E and Hb F could help in differential diagnosis of these Hb E related disorders commonly encountered in the regions where access to molecular techniques is limited.     

Analysis of fetal blood using capillary electrophoresis system: a simple method for prenatal diagnosis of severe thalassemia diseases

Introduction: Prenatal diagnosis of severe α‐ and β‐thalasssemia diseases is usually performed by DNA analysis. Objective: To establish a simple method, we have evaluated the reliability of prenatal diagnosis by fetal blood analysis using automated capillary electrophoresis system. Methods: Forty‐seven fetal blood specimens collected by cordocentesis at 18–28 wk of gestation were analyzed by the capillary electrophoresis system (Sebia). Fetal DNA was analyzed for respective thalassemia alleles by PCR. Results: Among 47 fetuses, 20 were at risk for the Hb Bart’s hydrops fetalis. DNA analysis identified four cases of homozygous α°‐thalassemia (SEA type). Hb analysis by the capillary electrophoresis demonstrated a major peak of Hb Bart’s (78.4–81.3%), Hb H (0.8–1.4%) and minor peaks of presumably embryonic Hbs. No Hb F and Hb A was observed. The level of Hb Bart’s was found to be 3.4–5.8% in unaffected heterozygote whereas normal fetus had no Hb Bart’s. Among the remaining 27 fetuses at risk for Hb E‐β‐thalassemia, DNA analysis identified 12 affected fetuses. Hb analysis showed Hb F (94.9–98.9%) and Hb E (1.1–1.8%) without Hb A in all cases. The levels of Hb A were found to be (4.3–7.2%), (1.0–5.5%) and (2.1–3.9%) in normal, heterozygous Hb E and heterozygous β‐thalassemia fetuses, respectively. Affected and unaffected fetuses could be easily distinguished. Conclusion: Capillary electrophoresis system is a simple and automated procedure for accurate prenatal diagnosis of severe thalassemia diseases which could readily be performed in routine setting.