Hb Nile[A1] and Hb Nile[A2]: novel identical [alpha77(EF6)Pro-->Ser] variants found in either the alpha1- or alpha2-globin genes.

We describe a novel hemoglobin (Hb) variant, caused by a CCC > TCC transition at codon 77 on the alpha gene. The mutation was found in two unrelated patients, in one patient on the alpha1 gene and in the other patient on the alpha2 gene. Both are anemic patients of African origin. Due to the neutral Pro-->Ser substitution, Hb Nile could not be separated from Hb A with common short-run screening methods for high performance liquid chromatography (HPLC) and capillary electrophoresis, but was evidently present after prolonged cation exchange HPLC or separation by isoelectric focusing (IEF). Reversed phase HPLC separation of the globin chains revealed the normal and abnormal alpha chains with an expression of about 20% for Hb Nile[A1], indicative of normal expression and stability of the mutant protein.