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.

Objectives: To report the hematological and molecular features as well as diagnostic aspects of the hitherto un-described interactions of two rare α-globin chain variants with α⁰-thalassemia commonly found among Southeast Asian populations. Methods: The study was done on two adult Thai patients (P1 and P2) who had hypochromic microcytic anemia. Hb analysis was carried out using high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). Mutations were identified by PCR and related techniques. Results: Hb analysis of P1 using HPLC showed a normal Hb pattern, but CE demonstrated an abnormal peak at zone 7. DNA sequencing identified a CCG-CTG mutation at codon 95 of the α2 globin gene corresponding to the Hb G-Georgia [α95(G2)Pro → Leu(α2)] previously undescribed in the Thai population. In contrast, Hb analysis of P2 demonstrated an abnormal peak not fully separated from Hb A on HPLC, but not on CE. DNA analysis identified the rarely described Hb Nakhon Ratchasima [α63(E12)Ala → Val(α2)] mutation. Routine DNA analysis detected the SEA deletion α⁰-thalassemia in trans to the Hb variants in both cases. Hematological parameters were compared with those of patients with compound heterozygote for other α-globin variants and α⁰-thalassemia previously documented. Conclusions: Identification of the patients confirmed that interaction of these rare Hb variants with α⁰-thalassemia does not lead to the Hb H disease. Differentiation of these two Hb variants from other clinically relevant hemoglobinopathies in a routine setting is, however, necessary. This can be accomplished using a combined Hb-HPLC and CE analysis followed by PCR-RFLP assays.

Objective:. To evaluate the ARKRAY ADAMS A1c HA-8180T analyzer for diagnosis of thalassemias and hemoglobinopathies commonly found in the Southeast Asi

Hemoglobin Constant Spring (Hb CS) and Hb Pakse' (PS) are the common non-deletional α⁺-thalassemia found in Thailand. These two variants can cause severe thalassemia syndromes, especially in fetus and neonate. Molecular diagnosis is the only confirmatory method because Hb CS and Hb PS are usually missed by routine screening and Hb analysis. Therefore, we aimed to develop rapid direct PCR for the diagnosis of Hb CS and PS genes. Multiplex direct PCR assays for identifying the Hb CS and PS genes in whole blood (WB) and amniotic fluid (AF) specimens were developed. The assays were firstly validated on 290 unrelated whole blood specimens. Hb CS and PS carriers were identified in 67 (23.1%) and 6 (2.1%) cases, respectively. A 100% concordant result as compared to routine PCR assay was observed. The direct PCR assays have been applied successfully for prenatal diagnosis in two families. The result showed that the fetuses were affected by homozygous Hb CS and compound heterozygous Hb CS/Hb PS. Accurate prenatal diagnosis of these families was observed using the newly developed assays. These assays should be applicable in routine thalassemia diagnostics as well as in the large-scale screening of Hb CS and PS in the region.