Poster Presentation Indian Ocean Rim Laboratory Haematology Congress 2019

Cord blood screening for thalassemia in the newborns: The value of Hb Bart’s, MCV and MCH as non-invasive screening parameters. (#121)

Wan Asmuni Wan Mohd Saman 1 , Rosline Hassan 2 , Syafini Md Yusof 2 , Rosnah Bahar 2
  1. Department of Pathology, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh, Selangor, Malaysia
  2. School of Medical & Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia

Introduction 

Thalassemia and hemoglobinopathies are major public health problems worldwide. Newborn screening for thalassemia and haemoglobinopathies has been recommended as a tool for morbidity prevention in many countries particularly for the screening of sickle cell diseases. In Southeast Asia countries, where the alpha and beta thalassemia are more prevalent, the screening of thalassemia and haemoglobinopathies has not been included in the newborn screening program. This could be due to the high cost for the molecular testing if the test is being performed on all newborns. Early detection of alpha thalassemia particularly haemoglobin H (Hb H) disease during newborn screening has enabled the observation of clinical phenotype of the disease. Hb Bart’s in cord blood has long been recognized as an accurate indicator for α-thalassemia. The level of Hb Bart’s is increased accordingly with the increasing number of defective α-gene. 

Objective  

The purpose of this study is to assess the effectiveness of MCV, MCH and Hb Bart’s as simple screening methods for thalassemia screening in newborn.  

Methodology  

A cross sectional study was done by collecting 300 cord blood samples which were analysed for red cell indices and haemoglobin analyses using capillary electrophoresis (Sebia CAPILLARYS2). DNA analysis were performed for three common deletional defect α-thalassemia in Malaysia. (--SEA, -α3.7 and –α4.2).  

Results  

The most prevalent haemoglobin disorder in our study was Hb E trait which was observed in 31 cases (10%) followed by 27 cases (9%) of α-thalassemia trait. There were two cases (0.6%) of Hb E with single α-gene deletion. Out of 300 cases, 16 were positive for Hb Bart’s with only eight of them confirmed to carry α-thalassemia gene. One of newborns with Hb Bart’s confirmed to have two α-gene deletions. However 21 newborns without Hb Bart’s were also found to have single α-gene deletion. The sensitivity of Hb Bart’s for the diagnosis of α-thalassemia was only 27.5%. The best cut off value for MCV and MCH were 101.5 fL and 33.7pg respectively with sensitivity of 85.8% for MCV and 88.7% for MCH. These two parameters were predictive for the diagnosis of α-thalassemia in newborn (p < 0.001).  

Conclusion 

The MCV and MCH are useful for prediction of α-thalassemia in newborns, whereas Hb Bart’s was found to be not predictive for single α-gene deletion Cord blood sampling is a useful method for thalassemia screening as it is less invasive and more readily accepted by parents for screening purposes. 

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