RESUMO
OBJECTIVES: Alpha-thalassemia (alpha-thal) is one of the most common genetic disorders and in some populations has prevalence as high as 30%. Disorders in hemoglobin (Hb) synthesis lead to mild to severe reduction in alpha-chain synthesis. Diagnosis of alpha-thal by examining fresh blood taken from umbilical cord is a simple and appropriate approach, while in later stages its diagnosis will be difficult and costly. MATERIAL AND METHODS: This study examined the prevalence of alpha-thal gene deletion in neonates in Sari, Iran. Screening study was carried out by examining fresh blood samples obtained from excised umbilical cords of neonates born in Sari hospitals from June 2007 to March 2008. Complete blood count (CBC) was done and Hb electrophoresis and High Performance Liquid Chromatography (HPLC) were performed for detection of Hb Bart's band. For each case two slides were stained by vital stain, 20 and 120 minutes post blood collection. Prevalence of alpha-thal was calculated and statistically analyzed (p < 5%). RESULTS: 69 cases out of 680 (10.1%) were positive for Hb Bart's. In 16 out of 69 positive cases (22.3%) the results of two methods, electrophoresis and slide staining were in conformity. In 53 positive cases (77%) there was no visible band in Hb electrophoresis; however Hb Bart's was detected via vital staining method. If the ratio of mean corpuscular volume (MCV) to red blood cell (RBC) count is smaller than 23, risk of alpha-thal is 2.8 fold greater than cases with an MCV/RBC ratio below 23 (p < 0.05). None of the cases were reported to be positive for Hb H disease and hydrops fetalis. CONCLUSIONS: Considering high prevalence of alpha-thal gene deletions in neonates in Sari hospitals, it is recommended to screen newborns for alpha-thal in this city and similar areas with such a high prevalence. The sensitivity of cellulose acetate electrophoresis and HPLC methods is not adequately high to detect Hb Bart's in all positive cases and staining and examination of peripheral blood slides stained with vital staining is necessary.
