Using Reticulocyte Indices to Identify Α-thalassemia– a Preliminary Report

Thalassemia poses an important public health problem in Thailand. The Ministry of Public Health of Thailand has conducted many programs for the control of thalassemia. These programs are useless if there is no effective, affordable method of screening for carriers. We report on the possibility of using an automated reticulocyte analyzer in order to identify α-thalassemia. Thirty-one control subjects and 14 couples, whose offsprings were affected with thalassemia H (7 α-thalassemia-1 and 7 α-thalassemia -2) were studied. We found that almost all reticulocyte parameters could be used as dianostic marker of α-thalassemia-1 carriers. Unfortunately, α-thalassemia-2 had only 5 parameters that were significantly different when compared to normal controls. This is the report to focus attention on the use of reticulocyte parameters in the screening of α-thalassemia. 1996; Smetanina et al, 1996; Peebies et al, 1987). We report on the possibility of using an automated reticulocyte analyzer to identify α-thalassemia. MATERIALS AND METHODS Study population We tested the possibility of using reticulocyte parameters in 14 couples whose offsprings were affected with thalassemia H (7 α-thalassemia-1 and 7 α-thalassemia -2). Twenty-one control subjects, who had normal blood cell indices, hemoglobin electrophoresis patterns and inclusion body studies, were recruited. All subjects gave the informed consent prior to the commencement of the study. Measurement of reticulocyte parameters An automated reticulocyte count analyzer was used: the automated hematology analyzer, TechniconH3 RTX. The Technicon-H3 RTX is an automated blood cell analyzer that performs CBCs and reticulocyte counts using an optical method that is based on the measurement of scatter and absorption of helium-neon laser light. The automated reticulocyte count method requires a preliminary manual mixing of 3μl of blood with 3 ml of reticulocyte reagent, containing a surfactant, which sphere red blood cells and reticulocytes, and the nucleic acid-binding dye, oxazine 750, which selectively stains reticulocytes. After a 15-minute incubation, the prepared sample is aspirated through the automated analyzer flow cell, where three directors measure laser scatter, and absorption. On a two-dimensional cytogram of absorption versus low angle scatter, the stained reticulocytes are separated from unstained erythrocytes, platelets, and leukocytes by appropriate thresholds. INTRODUCTION Thalassemia, a hemoglobin disorder, is the most common inherited disorder in Thailand (Flatz et al, 1965). At present, 500,000 Thai people suffer from this disorder, which is a major health problem in Thailand (Fucharoen and Winichagoon, 1997). This problem affects not only public health but also the economy of the country. If no specific control method are applied, then widespread disease can be expected. Carrier detection, genetic counseling, and prenatal diagnosis should be encouraged (WHO Working Group, 1983). The Ministry of Public Health, Thailand has established many programs for the control of thalassemia. However, these programs will be useless if there is no effective and affordable method of screening for carriers. The two common types of thalassemia are αthalassemia and β-thalassemia. A number of methods, including hemoglobin electrophoresis, are used to screen for these diseases (Kaewboworn, 1985; Paritpokee et al, 1999). However, α-thalassemias cannot be detected by simple hemoglobin electrophoresis; the gold standard method of screening for α-thalassemia is genotype study. Some recent studies have provided information about the difference between mRNA ratios in the reticulocytes of normal adults and individuals with αglobin gene deficiencies. Some studies have mentioned the value of the reticulocyte count in the identification of hemoglobin disorders. (Onofrio, 1996; Paterakis, Correspondence: Suphan Soogarun, Department of Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand. SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 160 Vol 33 (Suppl 3) 2002 Fig 1Graphic printout from a Technicon H 3 reticulocyte analyzer provides information regarding the staining intensity and cellular indices the of the reticulocyte population of the normal control group. Fig 2Graphic printout from a Technicon H 3 reticulocyte analyzer provides information regarding the staining intensity and cellular indices of the reticulocyte population of the α-thalassemia-1 group.