Differential role of Kruppel like factor 1 (KLF1) gene in red blood cell disorders

The master erythroid regulator KLF1,plays a pivotal role during erythroid lineage development by regulating the expression of many erythroid genes. Variations in the KLF1 gene are found to be associated with varied erythroid phenotypes. With the aim of determining the role of KLF1 gene variations in HbF induction and their genotype phenotype relationship, in this study, we screened 370 individuals with different hemoglobinopathy condition. Hematological analysis was carried out using automated blood cell counter and Variant II HPLC (Biorad). KLF1 gene mutations were screened using automated DNA sequencing. Expression analysis was carried out using q-RT PCR of KLF1, BCL11A and γ-globin after selective enrichment and culturing of CD 34 +ve cells into an erythroid lineage. Over all 14 KLF1 gene variations were identified, of which six variants were novel. The incidence of KLF1 gene mutations was found to be 8.1%. It was seen that KLF1 mutations contributed in borderline HbA₂ levels as 7.6% of our borderline HbA₂ cases showed presence of KLF1 variations. It also contributed in induction of HbF levels under stress erythropoietic conditions. Gene expression studies revealed inverse correlation of KLF1, BCL11A (reduced) with γ-globin gene expression (increased) in patients showing KLF1 gene mutations, thus indicating the role of KLF1 gene in regulating the γ-globin gene expression. The identification of genomic variants of the KLF1 may help in determining the functionally active domain of this protein and will facilitate in understanding the wide spectrum of phenotypes generated by these variants.