Department of Clinical Pathology, Tuen Mun Hospital, Hong Kong.
Department of Clinical Pathology, Tuen Mun Hospital, Hong Kong.
Pathology. 2023 Oct;55(6):835-842. doi: 10.1016/j.pathol.2023.05.008. Epub 2023 Jul 17.
The early eluting peaks in the first minute of cation-exchange high-performance liquid chromatography (CE-HPLC) are often not analysed in haemoglobin pattern studies, except for haemoglobin (Hb) Bart's and Hb H peaks. In this study, we described the presence of a specific α-thalassaemia early eluting peak (αEEP) at the retention time of 0.24 min generated by Variant II CE-HPLC (β-Thalassaemia Short Program; Bio-Rad Laboratories). We have evaluated the utility of αEEP for the screening of α-thalassaemia trait in our local Chinese population in comparison to the Hb H inclusion body test. A total of 303 blood samples presenting with microcytosis were sent for haemoglobin pattern study and were analysed for the presence or absence of αEEP and Hb H inclusions. Twenty cases with a normal mean corpuscular volume were assessed as a control. Discordant results between the αEEP and the Hb H inclusion test were reviewed with the α-globin genotyping test performed. The concordance rate of the αEEP and the Hb H inclusion body test was 96.0% (κ=0.921, p<0.001). Eight of 303 cases (2.6%) were initially negative for the Hb H inclusion test but positive for the αEEP. All eight cases were found to have occasional Hb H inclusion bodies upon review. Four of 303 cases (1.3%) were negative for the αEEP but positive for the Hb H inclusion test. Of these four cases, two (50%) showed heterozygous Southeast Asian (SEA) type deletion, one (25%) showed Hb Quong Sze mutation, and one (25%) showed no mutation detected upon molecular testing. All the Hb E trait cases with no Hb H inclusions and the negative control group showed the absence of the αEEP. The sensitivity and specificity of αEEP for detecting SEA deletion were 93.8% and 100% respectively, which is superior to the Hb H inclusion test (sensitivity 81.3%, specificity 95.2%). The αEEP is found to be a more sensitive method than the Hb H inclusion body test in the screening of α-thalassaemia trait in our Chinese population, in which SEA type deletion is prevalent. Further study is needed to explore the utility of the αEEP in the screening of α-thalassaemia traits in other populations. The exact nature of the αEEP is yet to be defined.
在阳离子交换高效液相色谱（CE-HPLC）的第 1 分钟内早期洗脱的峰通常不在血红蛋白模式研究中进行分析，除了血红蛋白（Hb）Bart's 和 Hb H 峰。在这项研究中，我们描述了在变异 II CE-HPLC（β-地中海贫血短程序；Bio-Rad Laboratories）中生成的特定的α-地中海贫血早期洗脱峰（αEEP）的存在，其保留时间为 0.24 分钟。我们评估了αEEP 在我们当地华人群体中筛查α-地中海贫血特征的效用，与 Hb H 包涵体试验进行比较。共有 303 个呈现小细胞低色素的血液样本被送进行血红蛋白模式研究，并分析存在或不存在αEEP 和 Hb H 包涵体。20 个平均红细胞体积正常的病例被评估为对照组。对αEEP 和 Hb H 包涵体试验之间的不一致结果进行了审查，并进行了α-球蛋白基因分型试验。αEEP 和 Hb H 包涵体试验的一致性率为 96.0%（κ=0.921，p<0.001）。303 例中有 8 例（2.6%）最初 Hb H 包涵体试验阴性但αEEP 阳性。所有 8 例在复查时均发现偶尔有 Hb H 包涵体。303 例中有 4 例（1.3%）αEEP 阴性但 Hb H 包涵体试验阳性。这 4 例中有 2 例（50%）显示杂合东南亚（SEA）缺失型，1 例（25%）显示 Hb Quong Sze 突变，1 例（25%）经分子检测未发现突变。所有无 Hb H 包涵体的 Hb E 特征病例和阴性对照组均未出现αEEP。αEEP 检测 SEA 缺失的敏感性和特异性分别为 93.8%和 100%，优于 Hb H 包涵体试验（敏感性 81.3%，特异性 95.2%）。αEEP 用于筛查我们中国人群中的α-地中海贫血特征比 Hb H 包涵体试验更敏感，SEA 缺失型在该人群中较为普遍。需要进一步研究来探讨αEEP 在筛查其他人群中α-地中海贫血特征的效用。αEEP 的确切性质尚待确定。
