A New Diagnostic Method for Premarital Screening of Thalassemia and Hemoglobinopathies: Microchip Electrophoresis (Gazelle) Method

Haemoglobinopathies constitute the most common recessive monogenic disorders worldwide. They consist of two main groups: Beta Thalassemia (BT) and sickle cell disease (SCD)¹. Recent estimates suggest that 7% of the world population are carriers and about 350,000 affected children are born every year². The majority of these (approximately 250,000) have SCD. The prevalence of these disorders is high in the Mediterranean Basin, some parts of Africa, the Middle East, India, Southeast Asia, Malaysia, and the Pacific Islands^3,4. Current screening methods include complete blood count (CBC), High Performance Liquid Chromatography (HPLC) or capillary electrophoresis. Molecular genetic confirmation by detecting pathogenic variants establishes the diagnosis. These methods require trained personnel and upgraded facilities, both of which may be lacking in many geographical areas where the disease is most prevalent. These standard laboratory methods also carry significant costs which may be unaffordable for most patients⁵. Gazelle is the first miniaturized, paper based, microchip electrophoresis platform for identifying the most common hemoglobin variants easily and affordably at point-of-care in low-resource settings ^6,7.

The aim of this study was to assess the performance of a low-cost, point-of-care (POC), microchip based cellulose acetate electrophoresis “Gazelle” compared to HPLC for premarital screening and confirm the possible variants with beta gene sequencing.

In this study, couples who visited the Hemoglobinopathy Diagnosis Thalassemia Center of Mediterranean Blood Diseases Foundation (MBDF) for premarital thalassemia screening were enrolled. CBC and HPLC tests were performed at MBDF. Gazelle test was performed at Antalya Genetic Diseases Assessment Center. A total of 516 participants were screened with CBC, HPLC and microchip electrophoresis (Gazelle). Then, Beta gene sequence analysis was performed on the positive samples for confirmation. As a control group, CBC, HPLC, microchip electrophoresis (Gazelle®), and Beta gene sequence analysis were performed on 100 beta-thalassemia and sickle cell carriers.

A total of 616 individuals participated in the study. Among the 516 individuals in the healthy group, 284 were women (55.1%), and 232 were men (44.9%), with an average age ± SD of 32.75 ± 11.25 years. A total of sixteen traits (3.2%) were identified as 14 beta-thalassemia trait, one Hb S, and one Hb D trait. The carriers consisted of 58 women (58%) and 42 men (42%), with an average age ± SD of 26.8 ± 18.6 years. As a control group, 100 carrier individuals (81 beta-thalassemia and 19 sickle cell trait) were included. The carriers consisted of 58 women (58%) and 42 men (42%), with an average age ± SD of 26.8 ± 18.6 years.

Analyses for comparing the devices were performed using IBM SPSS Version 29 software. The Kappa Analysis method was used to measure the diagnostic sufficiency of the two devices. Both devices were found to be 100% consistent in diagnosis. While assessing concurrence, subjects diagnosed with SCD BT by the microchip electrophoresis device were also found to have sickle cell or beta-thalassemia by the HPLC device (p<0.005). According to the Kappa analysis results, the closer the K value is to 1, the higher the compatibility between the devices. These analysis results indicate 100% compatibility between microchip electrophoresis and HPLC. Microchip electrophoresis (Gazelle) showed 100% sensitivity, specificity and accuracy when compared to HPLC.

Gazelle provides hemoglobin type identification and quantitative results of relative hemoglobin percentages for a broad range of hemoglobin variants including Hb A, Hb S, Hb F, and Hb A2, enabling accurate detection of BT carriers. Gazelle has many advantages over other laboratory tests, including timely results (in <8 min), digital storage, wi-fi connectivity, portability, and printed reports.

References

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2. Weatherall DJ. Blood. 2010;115:4331–4336

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5. McGann PT et al., Blood Cells Mol Dis. 2017 Sep;67:104-113

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7. An et.al. Lab Chip, 2021, 21, 3863