The relationship between the presence of extra α-globin genes and blood cell traits in Altamurana sheep

Abstract

Additional α-globin genes in sheep might produce extra α-globin chains and, consequently, the subject carrying triplicated (ααα) or quadruplicated (αααα) haplotypes may exhibit different hematological phenotypes when compared to the normal duplicated (αα) homozygotes (NN). Both ααα and αααα heterozygous (ND) and ααα and αααα homozygous (DD) individuals were obtained by selection and inbreeding. Chromatographic RP-HPLC analyses of the globin chains of 65 subjects (15 DD, 20 ND and 30 NN) were performed. A highly significant linear regression (r2 = 0.967) of the α/β ratio on the number of α-globin genes was found, and the α/β ratio ranged on average from 1.0 in NN individuals to 1.2 in the ND and 1.6 in the DD subjects. Values for blood fell within the range of normality but were rather peculiar as a whole. When the erythrocytes of individuals carrying normal arrangements were compared with those of subjects with extra α-genes, the latter had fewer erythrocytes that were bigger in size and had a higher Hb content and a greater osmotic fragility. This hematological picture is consistent with the existence of an unbalanced α/β ratio.