In order to determine the prevalence of thalassemia and hemoglobinopathies in different regions of northeast (NE) Thailand and Vientiane, Laos People's Democratic Republic (PDR), a total of 1,809 blood samples were collected consecutively from individuals attending antenatal care services at 11 community hospitals in different regions of NE Thailand and three hospitals in Vientiane, Laos PDR, from May 2009 to April 2010. All individuals were investigated for thalassemia and hemoglobinopathies using standard methods. For individuals from NE Thailand, the carrier frequencies were 41.7% for Hb E [β26(B8)Glu→Lys, GAG>AAG], 5.8% for α(0)-thalassemia (α(0)-thal), and 0.9% for β-thal. The THAI deletion type of α(0)-thal was found in one individual from an ethnic minority. From a group of pregnant Laotian women, 30.1% were Hb E carriers. The prevalence of α(0)-thal of 8.6% for the Laotian women was similar to that found in the upper northeastern part of Thailand. The frequency of β-thal was 2.3 %. The proportion of carriers of α(+)-thal and Hb Constant Spring (Hb CS, α142, Term→Gln (TAA>CAA in α2)] ) from Thailand and Laos was significantly different. The frequency of Hb Paksé [α142, Term→Tyr (TAA>TAT in α2)] was relatively low for Thailand as well as for Laos. The results indicate that thalassemia and hemoglobinopathies are a significant health burden in the region and that a prevention and control program for severe thalassemia diseases should be established in Laos.

Up to now, more than 200 different β-thalassemia (β-thal) mutations have been characterized. The majority are point mutations causing expression defects. Only approximately 10.0% of the defects are caused by large deletions involving the β-globin gene cluster causing β(0)-thal, (δβ)(0)-thal, (G)γ((A)γδβ)(0)-thal and other conditions with or without persistence of fetal hemoglobin (Hb). For the prevention of severe forms of β-thal intermedia and β-thal major, it is important to identify carriers of point mutations as well as carriers of deletions. β-Thalassemia and related disorders are most commonly present among populations from all Mediterranean countries as well as Southeast Asia, India, Africa, Central America and the Middle East. Twelve relatively frequently occurring deletion types have been described involving the β-globin gene cluster. These include the 105 bp β(0)-thal deletion, the 619 bp deletion, the 3.5 kb deletion, the Southeast Asian (SEA) deletion, the Filipino deletion, Hb Lepore, the Thai (δβ)(0)-thal, the Siriraj J (G)γ((A)γδβ)(0)-thal, the Chinese (G)γ((A)γδβ)(0)-thal, the Asian Indian deletion-inversion (G)γ((A)γδβ)(0)-thal as well as the (hereditary persistence of fetal hemoglobin) HPFH-6 and HPFH-7 deletions. To improve the rapid detection of the eight common β-globin cluster deletions in Southeast Asian countries, a simple molecular technique based on a single-tube multiplex gap-polymerase chain reaction (PCR) has been developed in this study. This technique provides a fast, simple and cost effective diagnostic test for deletion types of β-thal that can be applied in every molecular diagnostic laboratory having standard PCR equipment.

Context.—Thalassemia and hemoglobinopathies are major public health problems worldwide. To establish a cost-effective screening tool for newborns in regions where the incidence of these disorders is significant, study of the hemoglobin and hematologic features of normal and thalassemic newborns is necessary. Objective.—To study hemoglobin and hematologic characteristics of normal and various thalassemic newborns and to assess the effectiveness of simple screening methods for α-thalassemia 1 and hemoglobin E. Design.—Study was made of 402 cord blood specimens collected from unrelated Thai individuals. Hematologic parameters and hemoglobin profiles were determined. Thalassemia mutations were identified using polymerase chain reaction–related techniques. Results.—As many as 178 subjects (44.3%) were found to carry thalassemia genes with 18 different genotypes. All forms of α-thalassemia including double heterozygote for hemoglobin E and α-thalassemia showed significant reduction in hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin with increasing trend of red blood cell as compared with a non–α-thalassemic group. Although heterozygous hemoglobin E and β-thalassemia showed no hematologic difference from nonthalassemic group, heterozygous α-thalassemia 1 including those with hemoglobin E showed significant increase in hemoglobin Bart level. Conclusions.—Based on these findings, effective primary screening with 100% accuracy for α-thalassemia 1 and hemoglobin E in newborns in the region could be carried out using mean corpuscular volume less than 95 fL, mean corpuscular hemoglobin less than 30 pg, or hemoglobin Bart greater than 8.0% and hemoglobin E greater than 0.5%, respectively.