Genomic Variants in Members of the Krüppel-Like Factor Gene Family are Associated with Disease Severity and Hydroxyurea Treatment Efficacy in β-Hemoglobinopathies Patients

Abstract

Aim: β-Type hemoglobinopathies are characterized by vast phenotypic diversity as far as disease severity is concerned, while differences have also been observed in hydroxyurea (HU) treatment efficacy. These differences are partly attributed to the residual expression of fetal hemoglobin (HbF) in adulthood. The Krüppel-like family of transcription factors (KLFs) are a set of zinc finger DNA-binding proteins which play a major role in HbF regulation. Here, we explored the possible association of variants in KLF gene family members with response to HU treatment efficacy and disease severity in β-hemoglobinopathies patients. Materials & methods: Six tag single nucleotide polymorphisms, located in four KLF genes, namely KLF3, KLF4, KLF9 and KLF10, were analyzed in 110 β-thalassemia major patients (TDT), 18 nontransfusion dependent β-thalassemia patients (NTDT), 82 sickle cell disease/β-thalassemia compound heterozygous patients and 85 healthy individuals as controls. Results: Our findings show that a KLF4 genomic variant (rs2236599) is associated with HU treatment efficacy in sickle cell disease/β-thalassemia compound heterozygous patients and two KLF10 genomic variants (rs980112, rs3191333) are associated with persistent HbF levels in NTDT patients. Conclusion: Our findings provide evidence that genomic variants located in KLF10 gene may be considered as potential prognostic biomarkers of β-thalassemia clinical severity and an additional variant in KLF4 gene as a pharmacogenomic biomarker, predicting response to HU treatment.

Keywords::

• β-thalassemia
• hemoglobinopathies
• hydroxyurea
• Krüppel-like factors
• pharmacogenomics
• sickle cell disease

Supplementary data

To view the supplementary data that accompany this paper please visit the journal website at:

https://www.futuremedicine.com/doi/suppl/10.2217/pgs-2019-0063

Acknowledgments

This work was partly funded by European Commission grants to GPP. The authors gratefully acknowledge the expert technical assistance of S Tsekoura, K Tziolia and D Stamiri.

Financial & competing interests’ disclosure

GP Patrinos is full member and National Representative at the European Medicines Agency, Committee for Human Medicinal Products (CHMP) – Pharmacogenomics Working Party, Amsterdam, The Netherlands. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval and /or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, informed consent has been obtained from the participants involved in this study.