 It postulates that gene clusters were formed as a result of gene duplication and divergence.These gene clusters include the Hox gene cluster, the human β-globin gene cluster, and four clustered human growth hormone (hGH)/chorionic somaomammotropin genes.Conserved gene clusters, such as Hox and the human β-globin gene cluster, may be formed as a result of the process of "gene duplication and divergence".