Haemoglobin H-Constant Spring disease (––/ααCS) is caused by the co-inheritance of Hb Constant Spring and α0 thalassaemia. The anaemia is usually moderate, with a thalassaemia intermedia phenotype.

Hb Constant Spring is caused by a point mutation in the α globin gene. Most heterozygotes for Hb Constant Spring have the genotype (αα/ααCS), and have a thalassaemia trait phenotype.

The blood film features are identical to that of HbH disease.

Haemoglobin electrophoresis:

Alkaline gel electrophoresis from a patient with haemoglobin H-Constant Spring disease. The gel shows a fast band (red arrow) corresponding to haemoglobin H. There is also a very faint slow band (blue arrow) corresponding to Hb Constant Spring.

Acid gel electrophoresis from a patient with haemoglobin H-Constant Spring disease. The gel shows a band with the mobility of haemoglobin A. The band with the mobility between Hb A and Hb S likely represents degradation products.

HPLC:

HPLC from a patient with haemoglobin H-Constant Spring disease. There is a normal haemoglobin A band which results from the normal alpha gene interacting with the normal beta genes. There is a variant haemoglobin with a short retention time (1.25 min) corresponding to haemoglobin H. In addition, there is another variant haemoglobin in the C-window (blue arrow). This represents haemoglobin Constant Spring.

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