The hematological and molecular spectrum of α-thalassemias in Turkey: The hacettepe experience Türkiye’de alfa talasemilerin hematolojik ve moleküler spektrumu: Hacettepe deneyimi

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Ünal Ş., Gümrük F.

Turkish Journal of Hematology, vol.32, no.2, pp.136-143, 2015 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 32 Issue: 2
  • Publication Date: 2015
  • Doi Number: 10.4274/tjh.2014.0200
  • Journal Name: Turkish Journal of Hematology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, TR DİZİN (ULAKBİM)
  • Page Numbers: pp.136-143
  • Keywords: Molecular, Mutation, Turkey, α-Thalassemia
  • Hacettepe University Affiliated: Yes


Objective: The spectrum of a-thalassemias correlates well with the number of affected a-globin genes. Additionally, combinations of the several non-deletional types of mutations with a large trans deletion comprising the 2 a-globin genes have an impact on the clinical severity. The objective of this study was to analyze the hematological and molecular data of 35 patients with Hb H disease from a single center in order to identify the genotypes of Hb H disease and genotype-phenotype correlations. Materials and Methods: Herein, we report the hematological and mutational spectrum of patients with Hb H disease (n=35). Additionally, genotypes of a-gene mutations of 78 individuals, who were referred to our institution for a-gene screening, were analyzed. Results: Supporting the previous data from Turkey, -a3.7 was the most common mutation among patients with Hb H disease (62.8%) and in the other 78 subjects (39.7%). Of the patients with Hb H disease, the most common genotypes were -a3.7/--20.5, -a3.7/--26.5, and -a3.7/--17.5 in 10 (28.6%), 6 (17.1%), and 6 (17.1%) patients, respectively. Another small deletion, -4.2 alpha, and several non-deletional types of a-gene mutations, namely a(-5nt): IVS-I donor site (GAG.GTG.AGG->GAG.G-----); a(PA-2): AATAAA>AATGGA, and a(cd59): GGC->GAC, were found to be associated with Hb H disease when present at trans loci of one of the large deletions given above. The combinations consisting of 1 non-deletional and 1 of the large deletional types of mutations (aTa/--) at trans loci were found to result in a more severe phenotype compared to the genotypes composed of 1 small trans deletion of a large deletion (-a/--). The combination of a(Cd59) and -- in trans was associated with severe phenotype and the disease was associated with an increase in Hb Bart’s level with null Hb H. In spite of the presence of 2 intact a-globin genes, homozygosity for PA-2 mutation resulted in severe Hb H disease. Conclusion: This study indicated that Hb H disease is not rare in Turkey and its genotype is quite heterogeneous.