unstable hemoglobins

un·sta·ble he·mo·glo·bins

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 autooxidation and Heinz body formation and are associated with congenital nonspherocytic hemolytic anemia. The unstable β-chain abnormalities include Hb's Genova, Gun Hill, Hammersmith, Köln, Philly, Sabine, Santa Ana, Sydney, Wien, and Zürich; unstable α-chain abnormalities include Hb's Bibba, Sinai, and Torino.
References in periodicals archive ?
Unstable hemoglobins, hemoglobins with altered oxygen affinity, hemoglobin M and other variants of clinical and biological interest.
5]), Hb M anomalies, unstable hemoglobin variants, and easily oxidizable variants.
76 Glu]): an unstable hemoglobin causing hemolytic anemia.
However, unstable hemoglobins co-expressed with [alpha]-thalassemia minor can produce HbH disease in the same patient populations.
An interesting sickle cell compound heterozygote involving the unstable hemoglobin Volga produces a diagnostic dilemma.
Hb Sallenches [a104(GI 1) Cys>Tyr, TGC>TAC (a,2)]: an unstable hemoglobin variant found in an Indian child.
Two unstable hemoglobins are present in the blood and both have a higher affinity for oxygen than normal hemoglobin, resulting in poor oxygen delivery to tissues.
In most unstable hemoglobins one or more of these properties have been disrupted.
Unstable hemoglobins are hemoglobins that, because of the nature of the substitution, deletion, or insertion of amino acids (Table 3), tend to undergo spontaneous oxidation within the red cell and precipitate to form insoluble inclusions called Heinz bodies.
2) Hereditary hemoglobinopathies include abnormal hemoglobins: sickling disorders, unstable hemoglobins, abnormal oxygen affinities, and methemoglobins (hemoglobins M), disorders of hemoglobin chain production ([alpha] and [beta] thalassemias), and methemoglobinemias due to nicotinamide adenine dinucleotide diaphorase deficienc y.
Impaired binding of AHSP to [alpha] chain variants: Hb Groene Hart illustrates a mechanism leading to unstable hemoglobins with [alpha] thalassemic like syndrome.
Hemoglobin Debrousse [[beta]96(FG3)Leu[right arrow]Pro]: a new unstable hemoglobin with twofold increased oxygen affinity.