Authors: (including presenting author): :
Lam WK(1), Yuen CM(2), Tsui LLC(3), Li THS(4), Yeung VKP(5), Sin ACF(6), Wong TF(1), Fan CPY(1), Leung AYH(7), Yip SF(1)
Affiliation: :
(1)Department of Clinical Pathology, Tuen Mun Hospital, (2)Blood Cancer Cytogenetics and Genomics Laboratory, Department of Anatomical and Cellular Pathology, Princes of Wales Hospital, The Chinese University of Hong Kong, (3)Department of Pathology, United Christian Hospital, (4)Department of Pathology, Queen Elizabeth Hospital, (5)Department of Pathology, Princess Margaret Hospital, (6)Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, (7)Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong
Keyword 1: :
Alpha-thalassaemia
Keyword 2: :
Thalassaemia
Introduction: :
Although phenotypic screening for β-thalassaemia and other haemoglobinopathies using high-performance liquid chromatography (HPLC) is well-established, phenotypic screening for α0-thalassaemia has been limited by the lack of a reliable test for the locally important Southeast Asian type deletion (--SEA). To address this, we pioneered the use of the α-thalassaemia early eluting peak (αEEP) in HPLC for --SEA carrier detection.
Objectives: :
We aimed to translate the αEEP into clinical practice by elucidating its biochemical nature and comparing its diagnostic performance with other existing methods including microscopy (HbHi) and immunochromatographic strip test (ICT) in a multi-centre evaluation.
Methodology: :
A multi-centre diagnostic comparison study was performed across six tertiary referral hospitals in Hong Kong. The αEEP, HbHi and ICT were assessed by blinded observers against genotyping as the gold standard. Diagnostic performance was assessed in clinically relevant subgroups including β-thalassaemia carriers and elevated Hb F levels. The nature of the αEEP was investigated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Total manpower and reagent costs of each method were compared.
Result & Outcome: :
Among 820 patients, the αEEP showed superior diagnostic performance for detecting --SEA mutation (sensitivity 99.6%, specificity 100%) compared with HbHi (sensitivity 95.8%, P=0.006; specificity 97.3%, P< 0.001) and ICT (sensitivity 95.8%, P=0.006; specificity 75.4%, P< 0.001). The sensitivity of both HbHi and ICT was significantly lower in β-thalassemia carriers than in non-carriers (both tests: 54.6% vs. 97.6%, P< 0.001). The specificity of ICT was reduced when Hb F ≥1% compared with < 1% (68.6% vs. 78.0%, P=0.02). The αEEP remained robust across all subgroups. LC-MS/MS analysis revealed a strong association between the αEEP and ζ-globin chain (P< 0.001). Overall, the αEEP offered cost reductions of 98.6% relative to HbHi and 97.3% relative to ICT. The αEEP corresponds to embryonic ζ-globin chains and serves as a highly reliable, cost-effective marker for --SEA carrier detection in Hong Kong and potentially other prevalent regions. This finding enables a novel “all-in-one” HPLC screening strategy for --SEA, β-thalassaemia and other haemoglobinopathies.
