Springer Online Journal Archives 1860-2000
Summary With rare exceptions, the more than 600 human hemoglobin variants described are caused by a single point mutation. Other abnormal features, such as unequal crossing-over, frameshift mutagenesis or double mutations in the same polypeptide chain, have seldom been encountered. We report two new variants caused by such rare mutational events. Hb Zaïre [α116(GH4)-His-Leu-Pro-Ala-Glu-117 (GH5)] is the second example in which a short amino acid sequence is inserted within the α-chain. This abnormal hemoglobin results from a tandem repetition of 5 amino-acid residues, from sequence 112 through 116, at the end of the GH corner. Hb Duino is an unstable hemoglobin. It presents within the same β-chain, the association of two rare point mutations; these substitutions are those found in Hb Newcastle [β92(F8)His→Pro] and in Hb Camperdown [β104(G6)Arg→Ser]. Family studies demonstrated that the Hb Newcastle abnormality was a de novo mutation of a gene already carrying the Hb Camperdown substitution.
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