HB Mizuho or α₂β₂68(E12)LEU→PRO in a Young Dutch Boy

Abstract

Hb Mizuho is one of the more severely unstable hemoglobin (Hb) variants and is difficult to detect both by protein analysis and by sequencing of the amplified 3 chain. The instability is due to the introduction of a proline residue in helix E, of which five residues form part of the heme contact; a disturbance of this helix will undoubtedly destabilize the protein and decrease its ability to bind the heme group. Hb Mizuho was first detected in a Japanese girl using protein analytical methods (1), next in an Italian girl living in Chicago (2), while a third patient, from Kentucky, was identified through sequencing of amplified DNA (3). Here we summarize our experiences in identifying another carrier, a young boy from The Netherlands. Methodology used in the protein and DNA analyses has been detailed in Ref. 3.