Allen Angela, Perera Shiromi, Perera Luxman, Rodrigo Rexan, Mettananda Sachith, Matope Agnes, Silva Ishari, Hameed Nizri, Fisher Christopher A, Olivieri Nancy, Weatherall David J, Allen Stephen, Premawardhena Anuja
MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
Front Mol Biosci. 2019 Aug 9;6:66. doi: 10.3389/fmolb.2019.00066. eCollection 2019.
The high frequencies of carriers of severe haemoglobinopathies and of iron deficiency in Southeast Asia require reliable and affordable tests to improve on current screening procedures. We evaluate a "one stop" approach using the THALCON dichlorophenolindophenol (DCIP) and one-tube osmotic fragility (OF) tests and measurement of Zinc Protoporphyrin (ZPP) to detect and distinguish HbE and β-thalassaemia traits from iron deficiency. We compare findings with current screening practice in Sri Lanka that relies on the identification of low mean red cell volume and/or mean red cell hemoglobin for this purpose. Between November 2017 and May 2018, we undertook a cross-sectional survey of secondary school students in Gampaha district, Sri Lanka. The THALCON-DCIP and OF tests were compared to capillary electrophoresis (CE), used as a gold standard to detect haemoglobinopathies. ZPP was measured in whole blood. Plasma ferritin and C-reactive protein (CRP) were measured in students with a raised ZPP concentration. We collected venous blood samples from 1,324/1,332 (99.4%) students. The median age of the students was 17 (IQR 16-18) years, all were Sinhalese and 814/1,324 (61.5%) were female. CE identified 3 students with HbE trait and 26 students with β-thalassaemia trait. The THALCON-DCIP test was positive only in the 3 students with HbE (sensitivity 100%, 95% CI 29.2-100.0; specificity 100%, 95% CI 99.7-100.0). The THALCON-OF test identified all 26 students with β-thalassaemia trait (sensitivity = 100%, 95% CI 86.8-100.0) and 287 students with a normal CE result (specificity = 77.9%; 95% CI 75.5-80.1). It was also positive in 2/3 (66.7%) students with HbE trait. Iron deficiency (ZPP > 70 μmol/mol heme) was present in 118/1,240 (9.5%) students with a normal hemoglobin genotype, all of whom had plasma ferritin <15 ng/ml and CRP <5 mg/L. This one-stop approach offers reliable and affordable population screening for both haemoglobinopathy traits and iron deficiency in resource-limited settings where these conditions are common and ensures that iron supplements are targeted only to those who require them. Further work is warranted to refine the OF test to reduce the number of false positive results.
东南亚地区严重血红蛋白病和缺铁症携带者的高频率情况，需要可靠且经济实惠的检测方法来改进当前的筛查程序。我们评估了一种“一站式”方法，即使用THALCON二氯酚靛酚（DCIP）和单管渗透脆性（OF）试验以及测量锌原卟啉（ZPP），以检测和区分HbE和β地中海贫血特征与缺铁情况。我们将这些结果与斯里兰卡目前依赖于此目的识别低平均红细胞体积和/或平均红细胞血红蛋白的筛查实践进行比较。在2017年11月至2018年5月期间，我们对斯里兰卡甘巴哈区的中学生进行了一项横断面调查。将THALCON - DCIP和OF试验与用作检测血红蛋白病金标准的毛细管电泳（CE）进行比较。全血中测量ZPP。对ZPP浓度升高的学生测量血浆铁蛋白和C反应蛋白（CRP）。我们从1332名学生中采集了1324名（99.4％）学生的静脉血样本。学生的中位年龄为17岁（四分位间距16 - 18岁），均为僧伽罗人，1324名学生中有814名（61.5％）为女性。CE鉴定出3名具有HbE特征的学生和26名具有β地中海贫血特征的学生。THALCON - DCIP试验仅在3名具有HbE的学生中呈阳性（敏感性100％，95％CI 29.2 - 100.0；特异性100％，95％CI 99.7 - 100.0）。THALCON - OF试验鉴定出所有26名具有β地中海贫血特征的学生（敏感性 = 100％，95％CI 86.8 - 100.0）以及287名CE结果正常的学生（特异性 = 77.9％；95％CI 75.5 - 80.1）。它在2/3（66.7％）具有HbE特征的学生中也呈阳性。在1240名血红蛋白基因型正常的学生中，有118名（9.5％）存在缺铁（ZPP> 70 μmol/mol血红素），所有这些学生的血浆铁蛋白<15 ng/ml且CRP<5 mg/L。这种一站式方法为资源有限且这些病症常见的环境中的血红蛋白病特征和缺铁症提供了可靠且经济实惠的人群筛查，并确保铁补充剂仅针对那些需要的人。有必要进一步开展工作来改进OF试验以减少假阳性结果的数量。
