The first observation of two alpha globin mutations in Turkey: Hb Stanleyville II and a homozygous 5nt deletion

Abstract

Objective: In this study, we aimed to contribute prenatal diagnosis in the Çukurova region having high prevalence of hemoglobinopathies by implementing DNA sequencing analysis for the mutations undetectable by conventional methods. Methods: Hematological parameters of two families applied to Cukurova University Prenatal Diagnosis Center were analyzed. Hb variants were screened by cellulose acetate electrophoresis and by HPLC. DNA samples of cases were isolated using automatic DNA extraction machine. Microarray, RFLP, ARMS and Gap-PCR molecular methodologies carried out for determinations of hemoglobin mutations. Unidentified mutations were resolved by means of DNA Sequence Analysis. Results: We identified a previously unreported homozygous 5 nt deletional mutation [α2 IVS-1 134.-138. nt (TGAGG)] in Turkey by DNA Sequence Analysis. When we investigated twelve cases of this family by Gap-PCR and DNA Sequence Analysis it is observed that seven cases were heterozygous for 5nt deletion, a case found to be heterozygous 20.5 kb deletional mutation and four cases were found to be having no mutation. In the other family applied for prenatal diagnosis was observed to having Hb Stanleyville II [α2 78 (EF 7) Asn→ Lys (AAC→AAA)] mutation which is also a novel mutaion in Turkey. Mutations of eleven members of this family were determined by ARMS, RFLP, Gap-PCR and DNA Sequence Analysis, resulting in two cases heterozygous Hb Stanleyville II, five cases heterozygous 3.7 kb deletion, a case with heterozygous IVS-1-110 (G→C) mutation on β globin gene and three cases do not have any mutation. Conclusion: In this study, two types of mutations observed for the first time in Turkey have been identified.