Hb Karlskoga or alpha 2 beta (2)21(B3) Asp-->His: a new slow-moving variant found in Sweden.

An abnormal variant comprising approximately 39% of total hemoglobin was found in a 48-year-old Swedish woman. The variant was eluted from ion exchange high performance liquid chromatography (HPLC) used for routine quantification of Hb A1c at a position similar to Hb S. Amplification of beta-globin exons and nucleotide sequencing revealed heterozygosity for a GAT-->CAT mutation in codon 21, corresponding to the amino acid substitution Asp-->His at position 21. This mutation was confirmed by amino acid composition and peptide sequence determinations. Substitutions in this position are not likely to affect the function of the hemoglobin molecule and the hemoglobin variant, for which the name Hb Karlskoga is proposed, was not associated with any overt hematological abnormalities.