Unmasking Hb Paksé (codon 142, TAA>TAT,α2) and its Combinations in Patients also Carrying Hb Constant Spring (codon 142,TAA>CAA,α2) in Northern Thailand

Abstract

The incidence of Hb Paksé (codon 142, TAA>TAT, α2) might have been underestimated due to misidentifying some cases as Hb Constant Spring (Hb CS, codon 142, TAA>CAA, α2) since both abnormal hemoglobins (Hbs) migrate to the same position on Hb electrophoresis or chromatography. Multiplex asymmetric allele-specific polymerase chain reaction (PCR) for identification of Hb CS and Hb Paksé, and a real-time PCR (ReTi-PCR) with SYBR Green1 high resolution melting (HRM) analysis, for detection of the α-thalassemia-1 (α-thal-1) Southeast Asian (- -(SEA)/) type deletion, were performed on 114 blood samples collected from subjects who lived in northern Thailand. These samples were previously identified as carrying Hb CS by capillary electrophoresis (CE) or high performance liquid chromatography (HPLC). Five out of 114 (4.4%) samples were found to carry Hb Paksé with four different genotypes including Hb Paksé trait, compound Hb CS/Hb Paksé, Hb H-Hb Paksé disease and Hb H-Hb Paksé-Hb E disease. These results suggested that Hb Paksé and its various combinations can be misidentified as Hb CS. Although the clinical symptoms of Hb Paksé and Hb CS are similar, to prevent erroneous epidemiological data on Hb CS as well as underestimating the prevalence of Hb Paksé in northern Thailand, DNA analysis is recommended to be performed in all cases when peaks of Hb CS/Hb Paksé are detected on CE or HPLC.

Detection of Hb Constant Spring (HBA2: c.427T>C) Heterozygotes in Combination withβ-Thalassemia or Hb E Trait by Capillary Electrophoresis

“…Hb Paksé and its combinations with aand b-thal had been reported in northern Thailand (25). However, in the current study there were no samples carrying Hb Paksé.…”

High Resolution Melting Analysis: A Rapid Screening and Typing Tool for Common β-Thalassemia Mutation in Chinese Population

“…It not only could reduce the contamination risk, but also could be applied for high-throughput mutation scanning on genes for which large cohorts of patients has to be investigated. As early as 2008, Pornprasert S et al diagnosed some deletion forms and a few mutations of thalassemia by HRM analysis in Thailand successfully [9], [24], [25]. Recently, it has been used in the detection of β-thalassemia mutations in Chinese, but interference of SNP and Hb variants was still an embarrassment [10], [11].…”

“…Sensitivity and specificity of HRM for mutation detection are extremely high, and this technique also has the advantages of low cost and high throughput. Recently, this technique has also been used in the detection of α- and β-thalassemia [9], [10], [11], but there is no systemic study on the diagnostic capability of HRM to identify β-thalassemia. In the previous reports, the major interference was the SNP in hemoglobin-β gene such as rs713040, rs10768683 and rs1609812, which reduced the accuracy.…”

Iron deficiency anemia interfering the diagnosis of compound heterozygosity for Hb constant spring and Hb Paksé: The first case report

“…Molecular screening in selected populations in Thailand found HbCS to be approximately 10 times more prevalent than Hb paksé (5%‐5.8% vs 0.5%‐1.5%) . One study found Hb Paksé and its combinations, including compound HbCS/Hb Paksé, in 4.4% of patients who were previously diagnosed as HbCS . This present report underlines the importance of DNA analysis in patients who have been diagnosed as HbCS from electrophoresis or HPLC.…”