The alterations that involve globin chains are due to modifications in genes responsible for the sequence and structures of each polypeptide chain, as well as to regulator genes of the synthesis. Variant hemoglobin presents different chemical structure from the corresponding normal hemoglobin, resultant of mutations in one or more bases, causing change of amino acids in the alpha, beta, delta or gamma chain. The hemoglobin N is a beta globin variant, with substitution of lisina, in the position 95, for a glutamic acid, promoting electrophoretic mobility faster than the hemoglobin A in alkaline pH. In electrophoretical analysis of blood donor from São José do Rio Preto, SP, a carrier of hemoglobin N was identified in heterozygous, confirmed by isoelectric focusing and HPLC. The hemoglobin studies in blood donors permit the identification of rare variants and facilitate the genetic counseling and familial study.
Hemoglobin N; Globin chain; Abnormal hemoglobins
