PREVALENCE OF ß-THALASSEMIA MUTATIONS AMONG NORTHEASTERN IRANIAN POPULATION AND THEIR IMPACTS ON HEMATOLOGICAL INDICES AND APPLICATION OF PRENATAL DIAGNOSIS, A SEVEN-YEARS STUDY

Abstract

Background and objective: ß-thalassemia results from a diverse range of mutations inside the hemoglobin subunit β (HBB) gene. In a study of β-thalassemia carriers and some of their at-risk fetuses in the Khorasan province of Iran we aimed to recognize the most common mutations in the region and to find a possible link between these mutations and some of the relevant hematological indices. Methods: Amplification-refractory mutation system-PCR (ARMS-PCR) was used to detect the typical HBB mutations among 1593 individuals, suspected of having a mutated HBB allele from March/2011 to January/2018. Sanger sequencing of HBB had been performed, where ARMS-PCR was uninformative. In some cases, reverse dot blot was utilized. Analysis of variance was used to compare parametric variables. Results: Among 1273 ß-thalassemia carriers, the prevalence of the mutations were reported as follows: IVS-I-5 (42.03%), IVS-II-1 (11.23%), Codons 8/9 (4.79%), Codon 44 (4.56%), codon 15 (3.53%), Los Angeles (2.91%), Codon 5 (2.75%), IVS-I-110 (2.51%), -88 (2.20%) and other mutations were less than 2% of all of the reported mutations. 644 conceptions were subjected to prenatal diagnosis, using chorionic villus sampling. 118 cases were reported as normal. 352 cases were detected as carriers. 174 cases were diagnosed as affected. There was a significant difference in mean corpuscular volume and hemoglobin A2 levels between the 9 most commonly reported mutation types (p<0.001). Conclusion: This study makes a reliable guide for ß-thalassemia diagnosis in the region. The possibility of a correlation between HBB mutations and hematological indices opens a gate of future investigations.

Keywords

• ß-thalassemia, mutation prevalence, complete blood count, prenatal diagnosis, Khorasan