Krüppel-Like Factor 1 Gene Mutations in Thalassemia Patients from North Iran: Report of a New Mutation Associated with β-Thalassemia Intermedia

Thalassemia is a hereditary disease with an autosomal recessive inheritance pattern resulting in reduced production of globin chains. Mutations in modifier genes can cause or affect thalassemia. Krüppel-like factor 1 (KLF1) is a modifier gene that was investigated in this study. Thirty-five Iranian β-thalassemia (β-thal) minor patients with hematological symptoms including Hb A₂ 3.0%, mean corpuscular volume (MCV) <75.0 fL, mean corpuscular hemoglobin (Hb) (MCH) <25.0?pg, and two β-thal intermedia (β-TI) patients in 50 subjects who carried no mutations on the HBB and HBA2 or HBA1 genes were investigated for all exons of the KLF1 gene by polymerase chain reaction (PCR) and sequencing methods. Of the 35 patients with a β-thal minor phenotype, one patient was heterozygous for the c.544T>C mutation in exon 2 of KLF1 and HBB: c.380T>G variant, Hb Dhonburi [also known as Hb Neapolis or codon 126 (T>G)]. The c.340T>C mutation was also found in exon 2 of the KLF1 gene with an allele frequency of 16.6% in the studied β-thal carriers. The two β-TI patients were homozygous for a new mutation c.942delA in exon 3 of KLF1. Mutations in modifier genes can cause or affect thalassemia. Therefore, exact investigation of globin genes and modifiers such as KLF1 is necessary in areas where globin gene disorders are most prevalent to understand the reason of clinical and hematological symptoms of thalassemia and facilitate newborn screening or prenatal diagnosis (PND) programs.     

Mutation in a Highly Conserved COOH-Terminal Residue of Krüppel-Like Factor 1 Associated with Elevated Hb F in a Compound Heterozygous β-Thalassemia Patient with a Nontransfusion-Dependent Thalassemia Phenotype

We present a patient with a compound heterozygosity codon 39 (C?>?T) (β⁰) [or β39(C5)Gln→Stop (G39X); CAG?>?TAG; HBB: c.118C?>?T] and –87 (C?>?T) (β⁺) (HBB: c.?137C?>?T) β-globin mutations, a non transfusion-dependent thalassemia phenotype and 97.0% fetal hemoglobin. A novel heterozygous mutation was identified in a highly conserved residue in the COOH-terminus of the Krüppel-like factor 1, R360H, that likely altered DNA-binding and impaired transactivation.     

Homozygous Mutation on the β-Globin Polyadenylation Signal in a Tunisian Patient with β-Thalassemia Intermedia and Coinheritance of Gilbert’s Syndrome

We report here the clinical, hematological and molecular data in a 50-year-old patient with β-thalassemia intermedia (β-TI) caused by a homozygous β⁺ mutation on the β-globin gene polyadenylation (polyA) signal (AATAAA>AAAAAA). β Haplotype analysis was accomplished by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Haplotype and framework analysis showed that this mutation is associated with the [????????+?+?+] β haplotype and framework 1 (CCGCT) (FW1). This mutation was previously reported in the heterozygous state in association with the codon 9 (+TA) mutation in a β-TI patient originating from Tunisia. To the best of our knowledge, this is the first report describing this mutation in the homozygous state. The case reported here, coinherited Gilbert’s syndrome, which is characterized by hyperbilirubinemia. This conclusion was reached by the investigation of the promoter region [A(TA)_nTAA] motif of the UGT1A1 gene, showing the (TA)₆/(TA)₇ genotype.     

Hb Filottrano [codon 120 (–A)]: A Novel Frameshift Mutation in Exon 3 of the β-Globin Gene Causing Dominantly Inherited β-Thalassemia Intermedia

We report a novel frameshift mutation in exon 3 of the β-globin gene, that, in the heterozygous state, leads to a β-thalassemia intermedia (β-TI) phenotype (marked anemia, splenomegaly, hyperbilirubinemia, jaundice, unbalanced synthesis of α/non-α chains in a 34-year-old Italian woman. This frameshift mutation, due to the deletion of the first nucleotide (–A) at codon 120, results in a β-globin chain that is elongated to 156 amino acid residues. These highly unstable abnormal chains precipitate in the erythroblasts as inclusion bodies, thus causing inefficient erythropoiesis and ultimately resulting in the observed dominant clinical phenotype.     

Molecular and Cellular Characterization of a New α-Thalassemia Mutation (HBA2:c.94A>C) Generating an Alternative Splice Site and a Premature Stop Codon

The identification of α-thalassemia (α-thal) due to point mutations has been increasing significantly with the advancement of molecular diagnostic tools. We describe here the molecular and cellular characteristics of the thalassemia mutation HBA2:c.94A>C, a novel point mutation affecting the α2-globin gene, causing a mild α-thal phenotype in a male patient of undisclosed ethnicity, investigated for unexplained microcytosis. The detected mutation is located at the penultimate nucleotide (nt) of the first exon which we postulated might affect pre mRNA splicing. While an in silico analysis did not predict any aberrant splice variants, experimental analysis using our in vitro model for gene expression studies showed utilization of a cryptic splice site at codon 15 that resulted in an aberrant splice variant. As a result, a frameshift in the reading frame of the mature mRNA was produced, leading to the formation of a premature termination codon (PTC) between codons 48 and 49 in exon 2. This in turn leads to nonsense mediated mRNA decay (NMD) and the phenotype of α-thal.     

Characterization of Hb Calvino (HBB: c.406G > A): A New Silent β-Globin Gene Variant Found in Coexistence with α-Thalassemia in a Family of African Origin

We report a new silent β-globin gene variant found in a family from Angola living in the north eastern Italian city of Ferrara. The probands, two young sisters, presented with hematological parameters compatible with a β-thalassemia (β-thal) minor but with normal Hb A₂ levels and normal hemoglobin (Hb) separation on high performance liquid chromatography (HPLC). Molecular analyses revealed a homozygosity for the common –α^3.7 (rightward) deletion and heterozygosity for a novel transition (GCT?>?ACT) at codon 135 of the β-globin gene, leading to an Ala?→?Thr single amino acid substitution that was inherited from the healthy father.     

Adult Onset of a Thalassemia Intermedia Genotype in Association with a − α− 3.7 Homozygosity. Hb G-Accra [β73(E17)Asp→Asn] in Combination with β- and α-Thalassemia in the Same Family

We present the case of a 39-year-old male of mixed Black and Chinese Surinamese origin referred because of abdominal pain and extreme tiredness. The patient reported that he had received a single blood transfusion in his youth and presented at intake with a severe microcytic hypochromic anemia. A chest X-ray and computer tomography (CT)-scan revealed bilateral mediastinal lymphadenopathy and interstitial infiltrates. Elevated Hb F (80%) and an unbalanced syntheis ratio (β/α = 0.18) were compatible with severe β-thalassemia (thal) intermedia. DNA analysis revealed a double heterozygoty for the ? 88 (C→T) and the IVS-II-654 (C→T) mutations in the presence of a homozygosity for the ? α^3.7 deletion. The two daughters of the proband were both heterozygous for the IVS-II-654 (C→T) mutation and the ? α^3.7 deletion. The youngest daughter also carried the Hb G-Accra [β73(E17)Asp→Asn] mutation, inherited from the mother. Hb G-Accra, a mutant of presumed Ghanaian origin, described as non pathological in the carrier, is reported for the first time in combination with a severe β⁺-thal. The molecular background, haplotype of the mutations and a new A→G polymorphism at ? 309, 5′ to the ^Gγ promoter, are reported.