HBB gene mutation spectrum of beta-thalasemia patients from Turkey.

Abstract

Beta-thalasemia is de����ined by the absence or decrease of beta globin viamutations of the HBB gene and is one of the most common hereditary disordersexisting in Turkey. With the mean carrier frequency of β-thalassemiabeing 2.1% in the general population, and rates as high as 10% concentratedin certain regions of the country, hemoglobin electrophoresis of the individualsat premarital stage and molecular diagnosis of the carrier individualsfor genetic counseling cannot be overstated. Targeted diagnosis of theHBB gene mutations can be readily obtained using commercially availablereverse dot blotting kits. A sequence analysis of the complete HBB gene coveringUTR and near-gene regions provides a 99% mutation detection rate.We report here a summary ����inding of HBB gene analysis for 163 Turkishpatients, along with their family members totaling 248 individuals, referredwith beta-thalassemia indications covering the period of 2010-2014. 39were found to have homozygous, 31 possessed compound heterozygous and63 possessed heterozygous mutations. Overall, a total of 205 alleles werefound to have mutations. The ����irst 15 frequented mutations covered 88%of the entirety of all mutations. The summary range is as follows: c.93-21-G>A (IVS1+110G>A) 30.7%; c.135delC (p.ser45fs) 7.8%; c.92+1G>A (IVSI-1) 7.8%; c.25_26delAA (p.Lys9Valfs) 5.9%; c.20A>T (p.Glu7Val) 4.9%;c.92+6T>C (IVS-I-6) 4.9%. We discuss that the commercial targeted kitsdetect up to 80% of the HBB mutations for our patients. Sequence analysisof the HBB gene from 5’ promoter (-250bp) to 3’ promoter region (*250bp)contributes 15% to the mutation detection rate.