Detection of a Rare Mutation in the Initiation Codon of the β-Globin Gene (HBB:C.2T > C; P.Met1Thr)

β-thalassemia is one of the most common inherited autosomal disorders in the northern Iraqi Kurdistan region. This study reports a rare mutation in the initiation codon of the β-globin gene (HBB: c.2T > C; p.Met1Thr) in an 11-year-old male with severe transfusion-dependent β-thalassemia. Molecular testing to uncover the mutations of the β-globin gene in the proband and his parents was performed by amplification and reverse hybridization. Sanger sequencing was conducted for further identification. A severe β-globin gene mutation in codon 8/9 [+G] was initially identified in the proband and his mother's DNA samples. However, the detection of only one β-globin gene mutation was not enough to elucidate the patient's severe phenotype. Thus, a rare mutation in the initiation codon was identified later in the proband and his father by Sanger sequencing. In thalassemias, the presence of a rare mutation should be suspected when the patient's genotype does not correlate with the phenotype.