Evaluation of beta globin gene mutations in beta thalassemia trait children in Aydin province and its environment

Objective: Beta thalassemia trait is seen in 2.1% of our population and is the most common cause of anemia after iron deficiency. There are few studies showing the effect of genotype on phenotype in children with beta thalassemia traits. The aim of this study was to determine the diversity of mutations in children with beta thalassemia in and around Aydın and to evaluate the effects of these mutations on complete blood count parameters and hemoglobin electrophoresis. Materials and Methods: Sixty-five patients diagnosed with beta thalassemia carriage between 01.01.2014-01.08.2019 in Adnan Menderes University Faculty of Medicine, Department of Pediatrics and Pediatric Hematology were included in the study. Complete blood count, hemoglobin electrophoresis and mutation analysis results were obtained from computer data system and patient files. Data were analyzed using SPSS 21.0 statistical program. Results: Of the 65 patients, 39 (60.0%) were male, 26 (40.0%) were female, and the mean age was 8.34±4.94 years. When the complete blood count parameters were examined, 87.7% had anemia, 100% had microcytosis and RDW elevation, 49.2% had hypochromia and 87.7% had RBC elevation. RDW level was ≥16 in 66.2% of the cases. Seventeen different mutations were detected. The gene region where mutations occur most frequently was on intron 1 (66.1%). The most common mutations were IVS I-110 (44.11%), IVS I-1 G>A Heterozygote (8.8%), IVS I-6 T>C Heterozygote (7.5%) and IVS II-745 (7.5%), respectively. The mean Hb level was 10.55 gr/dl, MCV level 58.44 fl, RDW level 16.51, RBC level 5680x10⁹/l, HbA2 level 4.77%, HbF level was 2.34% in patients with IVS I-110 mutation. Mutations detected in four patients (6.1%) with normal HbA2 were -87 C>T Heterozygote, IVS II 81 C>T Heterozygote, IVS I-6 T>C Heterozygote and c316-373 (IVSII-478 C>A Heterozygote). Mutations detected in 12 patients with HbF levels above 5% IVS I-110 (5 persons), IVS I-6, C, Codon 39 C>T Heterozygous, IVS I-116, c.25-26 del AA (p. lys9Valfs) Heterozygote, c.27dupG (p.Ser10valfs * 14), c316-373 (IVS II-478 C>A Heterozygote), -87 C>T Heterozygote. The Mentzer index was calculated as >13 in six patients (9.2%). The mutations seen in these patients were IVS I-110, c.27dupG (p.Ser10valfs * 14), c316-373 (IVS II-478 C> A Heterozygote), -87 C> T Heterozygote. There were four patients (6.1%) with an RDW index >220. Two of these patients had c.27dupG (p.Ser10valfs * 14) and others had c316-373 (IVS II-478 C>A Heterozygote), -87 C>T Heterozygote mutations. Mutations detected in four patients whose HbF levels were between 9.48-15.67 IVS I-116 T>G heterozygote, IVS I-110 G>A heterozygote, c.25-26 del AA (p.lys59valfs) heterozygote, c.27 dupG (p.Ser10) the valve was * 14) and three of these mutations were located in exon 1 with β ° mutation type and one in IVS I-110 with intron 1. Conclusion: The same mutations detected in BTT patients had different effects on complete blood count parameters, HbA2 and HbF levels, suggesting that these mutations are not effective on the phenotype alone, may have a role in other factors, and these factors should be elucidated. We think that BTT may also be present in patients with low RBC, Mentzer index ≥13 and RDW index ≥220, HbA2 <3.5, and the study of mutation analysis in these patients will contribute to the literature. Key Words: Beta Thalassemia Trait, Complete Blood Count Parameters, Beta Globin Gene Mutations, Hemoglobin Electrophoresis.