Hb constant spring

Hb-Constant Spring (18, 19) was the first variant discovered that has 31 additional residues at the COOH-termlnus of the a-chaln Comparable hemoglobins are Hb-Icarla and Hb-Koya-Dora, and Hb-Tak which has 10 additional residues at the COOH-termlnus... 

Patients with Hb Constant Spring present with slightly reduced Hb, MCV, and MCH with hypochromia and microcytosis in the peripheral blood smear. Iron studies are often normal. 

Several nondeletion a+-thalassemias have been described. Four mutations in the normal stop codon for the a-globin gene have been identified (Table 28-3). In these cells, the mutated codon specifies an amino acid, and translation continues beyond the normal point, extending the a chains by 31 additional amino acids. Synthesis is terminated by a stop codon downstream from the normal stop codon. Hb Constant Spring is relatively common in Southeast Asian populations. In heterozygotes, about 1% of the a-globin is Hb Constant Spring (25% is expected... 

Hemoglobin Constant Spring is commonly found in combination with a -thalassemia especially the —mutation. The clinical presentation of this combination results in a severe form of Hb H disease. 

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