Yossombat Changtrakul

A reliable screening protocol for thalassemia and hemoglobinopathies in pregnancy: an alternative approach to electronic blood cell counting.

Primary screening for thalassemia and hemoglobinopathies usually involves an accurate blood count using an expensive electronic blood cell counter A cheaper alternative method was tested by using a modified osmotic fragility (OF) test and a modified dichlorophenolindophenol (DCIP) test. Altogether 423 pregnant Thai women participated in this project. Hemoglobin patterns and globin genotypes were determined using an automated high-performance liquid chromatography analyzer and polymerase chain reaction analysis of alpha- and beta-globin genes. Among the 423 subjects, 264 (62.4%) carried thalassemia genes. The combined OF and DCIP tests detected all pregnant carriers of the 3 clinically important thalassemias, ie, alpha0-thalassemia, beta-thalassemia, and hemoglobin E with a sensitivity of 100.0%, specificity of 87.1%, positive predictive value of 84.5%, and negative predictive value of 100.0%, which show more effectiveness than these values for the standard method based on RBC counts. A combination of modified OF and DCIP tests should prove useful and applicable to prenatal screening programs for thalassemia and hemoglobinopathies in communities with limited facilities and economic resources.

Molecular and hematological profiles of hemoglobin EE disease with different forms of α-thalassemia

We describe hematologic and DNA characterization of hemoglobin (Hb) E homozygote with various forms of α-thalassemia in Thai individuals. Altogether, 131 unrelated adult subjects with Hb EE at routine Hb analysis were studied. Forty-two cases were found to carry α-thalassemia with ten different genotypes. These included 21 cases with α+-thalassemia heterozygote (–α3.7/αα), one case with α+-thalassemia heterozygote (–α4.2/αα), six cases with Hb Constant Spring heterozygote (αCSα/αα), four cases with homozygous α+-thalassemia (–α3.7/–α3.7), one case with homozygous α+-thalassemia (–α4.2/–α4.2), two cases with compound α+-thalassemia/Hb Constant Spring (–α3.7/αCSα), one case with compound α+-thalassemia/Hb Paksé (–α3.7/αPSα), four cases with α0-thalassemia heterozygote (––SEA/αα), and, unexpectedly, two cases with compound α0-thalassemia/α+-thalassemia [(––SEA/–α3.7) and (––SEA/–α4.2)]. The hematological expression of these Hb E homozygotes with various forms of α-thalassemia was presented comparatively with those of the 89 cases of pure Hb E homozygotes. Overlapping levels of Hb E, Hb F, and other hematological parameters were observed which did not predict clinical severity, indicating a need for α-globin gene analysis for accurate diagnosis and improved genetic counseling.

Thalassemia and hemoglobinopathies in Southeast Asian newborns: diagnostic assessment using capillary electrophoresis system

BACKGROUND We have investigated the Capillarys 2 Hemoglobin testing system to assist in presumptive diagnosis of thalassemia and hemoglobinopathies commonly found in Southeast Asia. METHODS Study was conducted on 226 newborns. Hematological parameters were recorded and Hb profiles were examined on the Capillarys 2 Hemoglobin analyzer (SEBIA). DNA analyses were used to establish the final diagnoses. RESULTS Among 226 newborns examined, 122 had thalassemias with 17 different genotypes. The capillary electrophoresis system could provide useful data for presumptive diagnoses of cases, especially those with Hb E and α-thalassemia. Hb E was found to be 2.6-6.2% in heterozygote whereas Hb Barts were clearly observed in cases with compound heterozygous or homozygous α(+)-thalassemia and heterozygous α(0)-thalassemia. Hb H disease and other forms of α-thalassemia could be differentiated based on the presence of Hb Barts and its percentage. CONCLUSION The capillary electrophoresis system is applicable to newborn screening for common forms of thalassemia in Southeast Asia.

H63D Mutation of the Hemochromatosis Gene and Serum Ferritin Levels in Thai Thalassemia Carriers

We determined the prevalence of the H63D and the IVS5#1G-A HFE mutations in 370 (169 males and 201 females) Thai thalassemia carriers and 201 normal subjects. While no IVS5#1G-A mutation was found, the H63D heterozygosity was identified in 5.5% (11/201) of normal subjects and 7.3% (27/370) of thalassemia carriers. Within the thalassemic group, the medians (ranges) of serum ferritin were 217.5 ng/ml (20.1–424.3) and 169.8 ng/ml (3.9–3,536.0) in male subjects and 30.4 ng/ml (11.9–130.7) and 49.3 ng/ml (0.6–931.0) in female subjects with (HD) and without (HH) H63D mutation, respectively. The proportions of subjects with elevated ferritin were found to be 37.5% (6/16) for HD and 14.0% (18/129) for HH in male and 0% (0/11) for HD and 3.0% (5/164) for HH in female subjects, respectively. Statistical analysis of all the data revealed no significant difference. Among 14 Hb E/β-thalassemia patients, no difference in hematological data as well as serum ferritin levels was observed between those with (HD) and without (HH) H63D mutation. Therefore, the H63D heterozygosity has no significant effect on the serum ferritin level and screening for this HFE mutation in thalassemic patients is not recommended.

Association of Hb Thailand [α56(E5)Lys→Thr] and Hb Phnom Penh [α117(GH5)-Ile-α118(H1)] with α0-Thalassemia: Molecular and Hematological Features and Differential Diagnosis

We report the molecular and hematological characteristics of two rare hemoglobin (Hb) variants found in associations with a common α0-thalassemia (α0-thal) in Thai patients. The first case (P1) was a generally healthy 27-year-old man discovered during our ongoing thalassemia screening program. Hemoglobin and DNA analyses identified a previously undescribed condition of compound heterozygosity for Hb Thailand [α56(E5)Lys→Thr] and α0-thal (SEA deletion). The second case (P2) was a 4-year-old boy with hypochromic microcytic anemia. Hemoglobin and DNA analyses also identified a compound heterozygosity for Hb Phnom Penh [α117(GH5)-Ile-α118(H1)] in association with α0-thal (SEA deletion). Although Hb H (β4) inclusion bodies were observed in both cases, Hb analysis using both high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) did not show Hb H. While the two Hb variants could be recognized on Hb HPLC analysis, their corresponding Hb A2 derivatives: the Hb A2-Thailand and Hb A2-Phnom Penh, were clearly observed on CE. Apparently, combination of these two Hb variants with α0-thal are not expressed as Hb H disease. The two Hb variants could be confirmed by polymerase chain restriction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific PCR assays.