The New -474(C→T) Substitution Discovered in the HBG2 Promoter of a Sardinian δβ-Thalassemia Carrier

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.

Biochemical and Molecular Analysis of the Hb Lepore Boston Washington in a Syrian Homozygous Child

Hemoglobin (Hb) Lepore is composed of two normal α chains and two δβ fusion globins that arise from unequal crossover events between the δ- and β-globin genes. The Hb Lepore is widespread all over the world and in many ethnic groups. It includes some of the few clinically significant Hb variants that are associated with a β-thalassemia phenotype. Here, we describe the first occurrence of Hb Lepore Boston Washington in a Syrian individual. The patient, a 10-year-old child, shows severe anemia with a Hb level of 6.85 g/dL and typical thalassemic red cell indices. The diagnostic procedure implies hematological, biochemical, and molecular analysis, including multiplex ligation-dependent probe amplification (MLPA) assay, GAP-PCR, and DNA sequencing. This latter allowed us to define the correct structure of the hybrid δβ-globin gene. The knowledge of the spectrum of mutations associated with different geographical areas is the prerequisite to set up large-scale screening programs and be able to offer genetic counseling to couples at risk.

A Novel -72 (T→A) β-Promoter Mutation Causing Slightly Elevated HbA2 in a Vietnamese Heterozygote

We report a novel β⁺-thalassemia mutation found in a Vietnamese family. The molecular defect T→A lies at -72 of the β-globin gene promoter, within the conserved CCAAT box. The index case was a 5-year-old child having red blood cells indices close to normal and slightly increased level of HbA₂ (3.96%). The expression of the mutated β allele was inferred by luciferase reporter assay in K562 cells. The β -72 determinant is the eighth β-thalassemic mutation identified in Vietnam and it was not previously reported in any population. The absence of homozygous or compound heterozygous states did not allow us to precisely predict either its clinical impact or its relevance in management programs. Our results further underline the importance of identifying and characterizing new or rare β⁺-thalassemic alleles in carrier screening and prenatal diagnosis.