Molecular Basis ofβ-Thalassemia in the Population of the Aegean Region of Turkey: Identification of A Novel Deletion Mutation

Abstract

β-Thalassemia (β-thal) is the most common monogenic disorder in Turkey. The aim of this study was to investigate the spectrum of β-thal mutations in the Aegean region of Turkey. The data was derived from 1171 unrelated β-thal subjects, detected in a regional reference hospital between November 2004 and December 2013. Screening for the 22 common mutations was performed using the polymerase chain reaction (PCR)-reverse dot-blot method, and direct automated DNA sequencing for the unknown samples. Thirty-one different β-thal alleles were identified. Seven mutations, namely IVS-I-110 (G > A) (41.7%), IVS-I-1 (G > A) (8.9%), IVS-II-745 (C > G) (8.6%), codon 8 (-AA) (7.7%), IVS-II-1 (G > A) (7.2%), IVS-I-6 (T > C) (6.6%), codon 39 (C > T) (4.6%) accounted for 85.3% of the mutated alleles. Frequencies of the remaining 24 β-thal mutations were less than 2.2%; these included one novel mutation [HBB: c.206_212del (p.Leu69Profs*19)], and four others [-56 (G > C), codon 16 (-C), IVS-I (-3) (C > T) (codon 29), codon 76 (-C)] found in Turkey for the first time. The results will help to prevent severe β-thal through genetic counseling and prenatal diagnosis (PND) in the Aegean region of Turkey.

A National Registry of Thalassemia in Turkey: Demographic and Disease Characteristics of Patients, Achievements, and Challenges in Prevention

“…The wide molecular heterogeneity of Turkish thalassemic subjects has been confirmed by this registry. The most common seven mutations accounted for less than 80% of all thalassemia alleles, consistent with previous reports from Turkey [ 15 , 16 , 17 , 18 , 19 , 20 ]. The IVS-I-110(G->A) substitution was the most common defect with a frequency of 47% within all b-thalassemia alleles in the cohort.…”

Trakya Üniversitesi Tıp Fakültesi Genetik Hastalıklar Tanı Merkezinde beta talasemi minor kliniği ile incelenen bireylerde görülen beta globin mutasyonları ve sıklığı

“…Beta-globin (HBB) geni 11. kromozomun kısa kolu üzerinde (11p15.4) yer almakta ve üç ekzon, iki intron içermektedir. HBB gen mutasyonları beta talasemi, orak hücreli anemi ve anormal hemoglobin varyantlarına neden olmaktadır (2). Beta-talasemi hemoglobin tetramerindeki beta globin zincirinin yokluğu (beta 0 ) veya azalması (beta + ) ile karakterizedir.…”