Duplication of the hemoglobin alpha-chain gene in sheep: characterization of a new alpha-chain variant present in animals possessing the alpha Leu and the II alpha His chains.

The structural characterization of a third type of alpha chain, detected in the hemoglobin of sheep also possessing the alpha Leu and the II alpha His chains, is reported. The new alpha-chain variant is an allele of the common alpha Leu chain controlled by the 1 alpha locus and differs from it in the replacement of the serine residue at position 8 with an alanine (I alpha 8 Ser leads to Ala). The alanine variant was observed in 38 of 206 sheep, whose hemolysates were analyzed by isoelectric focusing, and was found exclusively among the 57 animals also possessing the II alpha His chain.