Spectrum of beta- thalassemia mutations in various ethnic regions of Iran

ABSTRACT

Thalassemia is a group of inherited disorders characterized by reduced or absent amounts of hemoglobin, the oxygen-carrying protein inside the red blood cells. beta-Thalassemia, one of the most widespread genetic disease in the world, is a common autosomal recessive disorder generally caused by point mutations in the beta-globin gene that is located as a cluster on the short arm of chromosome 11[OMIMMIM # 141900]. The objective of this study was to identify spectrum of Beta Thalassemia mutations in various ethnic regions of Iran. We extracted and differentiated the Iron deficiency patients with the help of 10 discrimination indices [Mentzer Index, England and Fraser index, Srivastava ndex, Green and King index, Shine and Lal index, red blood cell [RBC] count, red blood cell distribution width, red blood cell distribution width index [RDWI], Mean Density of Hemoglobin per Liter of blood [MDHL] and Mean Cell Hemoglobin Density [MCHD]] from beta-thalassemia patients. In a total of 1098 carriers [1045 beta-thalassemia and 53 iron deficiency], we detected different beta-thalassemia mutations in the studied subjects of 5 different ethnic regions from Iran. beta-Thalassemia was diagnosed based on complete blood counts, Hb electrophoresis, and ASO-Hybridization in patients from each area separately at Research center of Thalassemia and Hemoglobinopathies, Ahwaz Jondishapur University of Medical Sciences, Shafa Hospital, Iran. This study has shown that the most common mutation for each region was IVS.II-1 [G at'A] [34%] in Khuzestan, IVS I [3' end]-25 bp [28.7%] in Booshehr, IVS II- 1 [G at' A] [41.5%] in Fars, IVS-II-1 [Gat-' A] [31.8%] in Isfahan, IVS I-5 [Gat-' C] [44.8%] in Sistan- Baloochestan, respectively. The presence of such a high frequency of various local mutants alleles is strong support for role of non-isolating genetically areas. In likelihood, both founder effect and natural selection caused by migration from neighboring areas have complemented each other to produce the high frequency of unique alleles within each region