The Hemoglobin Polymorphism in Sardinian Goats: Nucleotide Sequence and Frequency of ßA, ßD, ß^D-Malta, and ßE Globin Genes

Abstract

As in most vertebrates, the goat α-globin gene locus is duplicated though producing ^Iα and ^IIα globin chains that differ in three amino acid residues [[1]–[3]]. As the result of an unusual evolutionary history, however, a goat (β-globin gene cluster consists of 12 genes organized as a triplicated four-gene set located on chromosome 7: 5’-ε^I-ε^II-ψβ^X-β^C-ε^III-ε^IV-ψβ^Y-β^A-ε^V-ε^VI-ψβ^Z-β^F-3’[[4]-[6]]. The β^A-globin gene is expressed in adult animals, whereas β^F and β^C genes are expressed in the fetus and in juveniles up to 6 months of age, respectively [[7]]. During the first year of postnatal life, the synthesis of pre-adult β^C-globin is supplanted by the synthesis of adult β^A. The β^C→β^A switch is reversible and the reactivation of the β^C synthesis, at the expense of β^A, can be induced by anemia, hypoxia, or the administration of erythropoietin [[1],[8]]. Due to this unusual feature, which is also common in sheep hemoglobin (Hb) type A and in Sardinian mouflon [[5], [7], [9], [10]], the organization of globin genes, the nucleotide sequence, and the evolution of goat and sheep globin genes have been extensively studied [[1]–[2], [11]–[13]].