α-Thalassemia Intermedia Results from Interactions of Unstable Hb Prato [α31(B12)Arg→Ser (HBA1 or HBA2 c.96G>T or C)] with the α-Thalassemia-1 [– –SEA (Southeast Asian)] Deletion in Thailand

Abstract

The clinical consequences of many abnormal hemoglobins (Hbs) interacting with α- or β-thalassemia (α- or β-thal) or other hemoglobinopathies have not been described. We evaluated a 75-year-old Thai woman and her 45-year-old daughter. Hematological data was obtained on an automated cell counter. Hemoglobin (Hb) analysis was carried out using high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) assays. Mutations and globin haplotypes were identified by appropriated DNA techniques. The proband presented with moderate anemia and inclusion bodies in most of the red blood cells (RBCs), while altered RBC parameters were absent in her daughter. Hemoglobin analysis showed an abnormal Hb peak only in the proband. DNA analysis identified a G>T substitution at codon 31 of the α1-globin gene, corresponding to Hb Prato [α31(B12)Arg→Ser (HBA1 or HBA2 c.96G>T or C)] in both subjects. The α-thal-1 [– –SEA (Southeast Asian)] deletion was also identified in the proband, but not in her daughter. These mutations could be identified using newly developed allele-specific polymerase chain reaction (ASPCR) assays. The α haplotypic analysis demonstrated the Thai Hb Prato allele was associated with haplotype [+ – S + – + –] [the S represents the inter ζ hypervariable region (HVR)]. The combination of the unstable Hb Prato with α-thal-1 result in α-thal intermedia (α-TI) phenotypes. A simple DNA method is essential for detection, and a haplotypic α-globin gene cluster are presented.