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Medical Definition of Unstable haemoglobins
1. A group of rare Hb's with amino acid substitutions (or amino acid deletions in three types) that alter the three-dimensional shape of the globin in a manner that renders the molecule unstable; they have an increased but variable tendency to auto-oxidation and Heinz body formation and are associated with congenital nonspherocytic haemolytic anaemia. The unstable b chain abnormalities include Hb's Genova, Gun Hill, Hammersmith, Koln, Philly, Sabine, Santa Ana, Sydney, Wien, and Zurich; unstable a chain abnormalities include Hb's Bibba, Sinai, and Torino. (05 Mar 2000)