Publication: Proportion of non-deletional alpha thalassaemia in Hospital Tengku Ampuan Rahimah (HTAR), Klang, Selangor
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Date
2022
Authors
Kalimuthu, Vasuhi
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Abstract
Introduction: Alpha (α) thalassaemia, caused by deletional and non-deletional mutations of the α-globin gene, is one of the most common haemoglobin genetic abnormalities. Non-deletional determinants of alpha thalassaemia produces highly unstable variants which are difficult to detect and may lead to HbH disease or even haemoglobin Bart hydrops fetalis syndrome when compounded with deletional mutations. Objective: This study aims to provide data on the proportion of non-deletional alpha thalassaemia at Hospital Tengku Ampuan Rahimah (HTAR), Klang, Selangor, to compare the haematological parameters (Hb, RBC, MCH, MCV, MCHC) of non-deletional alpha thalassaemia with the deletional variant and to determine the agreement between Capillary Electrophoresis and High-Performance Liquid Chromatography in detecting non-deletional alpha thalassaemia established by molecular analysis. Methods: A cross-sectional study involving data extraction from the HTAR haematology laboratory registry on confirmed thalassaemia cases via DNA analysis from January 2017 to December 2019. Haematological parameters and haemoglobin analysis results were obtained from the laboratory database. Samples were segregated into three groups according to the number of mutated genes. Results: We identified a total of 479 cases of alpha thalassaemia, from which 98 (20.5%) were non-deletional type. Among these, 75 (76.5%) were heterozygous Hb CS, 17 (17.3%) heterozygous Hb Adana, 3 (3.1%) heterozygous Hb QS and 1 (1.0%) case each of compound heterozygous Hb CS and Hb Adana (αCSα/αCD59α), compound heterozygous Hb CS and -3.7kb deletion (αCSα /-α3.7) and compound heterozygous of Hb CS and SEA deletion (αCSα/--SEA). In the single and double gene mutated groups, there was no significant difference of haematological parameters between both variants. In the third group, due to the very small number of sample size, statistical analysis was not done. Among the non-deletional variants, there was significant association between Hb, MCH and MCHC parameters and the number of mutated alpha genes. A total of 77 samples out of the 98 non-deletional cases showed positive findings on CE. However, of these 77 samples, only 40 samples underwent HPLC as the second screening method of haemoglobin analysis and from which 5 (12.5%) samples were detected by HPLC. Conclusion: This study showed that Hb CS is the most common non-deletional α thalassaemia in HTAR, Klang. We identified that Hb, MCH and MCHC may help as an effective screening tool for non-deletional alpha thalassaemia. We also revealed that there is a significant association between CE and HPLC in detecting Hb CS, and that CE is superior to HPLC.
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