Investigation of Alpha Globin Gene Mutations by Complementary Methods in Antalya

INTRODUCTION: Alpha (α) thalassemia syndromes are inherited autosomal recessively and caused by mutations on optionally one or more of the four α-globin genes (αα/αα). Alpha thalassemic mutations could be more commonly deletional or rarely non-deletional. While small deletional mutations such as -3.7 cause α+-thalassemia, large deletions such as -26.5 -20.5 cause α0-thalassemia. The objective of this study was to determine the spectrum of deletional and non-deletional α-thalassemia mutations in the Antalya population,Turkey.
METHODS: In this study, 250 individuals with low hematological values, normal Hb A2 who were not affected with beta thalassemia were investigated the presence of α-thalassemia mutations by reverse dot blot hybridization(RDBH) and, the confirmation of some positive and negative cases by multiplex ligation dependent probe amplification(MLPA), at the latest DNA sequencing.
RESULTS: Eight different mutations were determined in 112 (44.8%) of patients. The -αα3.7 deletion was the most common mutation(73.3%). Others common mutations were the – α 20.5 (13.0%) and –MED (6.5%), --FIL (2.4%), Hb Adana (2.4%). These five mutations make up 97.5 % of total mutations. Three patients with Hb H disease were found related with - α 3.7 /-(α) -20.5 genotype. One patient (2.04%) had the ααα anti-3.7 gene triplication. Two rare mutations, α2 codon 64 (G>C) (Hb Fontainebleau) and α2 codon 193 (G>A) (Hb G- Waimanalo) were determined by DNA sequencing firstly in Antalya Province, Turkey.
DISCUSSION AND CONCLUSION: Our results may be valuable to give accurate premarital genetic counseling, classical prenatal and preimplantation genetic diagnosis by the comlementary methods such as RDBH, MLPA and DNA sequencing on carrier screening.