**4.1 Alpha (α) globin gene cluster**

The α-globin gene cluster is located on the short arm of Chromosome 16 (16p13.3). The cluster includes three protein coding functional genes (α1, α2, and ζ2) and spans about 30 kb, and the genes are arranged in order as per their expression during developmental stages in human beings [17, 18].

The α1 and α2 gene are highly homologous and encode an identical protein and differs only in the sequences of non-coding regions [17, 19]. The α-globin gene codes for 141 amino acids and consist of 3 exons separated by two introns (**Figure 2**). The length of IVS 1 in both α 1 and α 2 gene is same having 117 nucleotides whereas IVS II of α1 consist of 149 and α2 is of 142 nucleotides.
