Haemoglobin E (HbE) disease

Haemoglobin E (HbE) is an extremely common structural hemoglobin variant that occurs at high frequencies throughout many Asian countries. It is a β-haemoglobin variant, which is produced at a slightly reduced rate and hence has the phenotype of a mild form of β thalassemia.

Its interactions with different forms of α thalassemia result in a wide variety of clinical disorders, whereas its coinheritance with β thalassemia, a condition called haemoglobin E β thalassemia, is by far the most common severe form of β thalassemia in Asia and, globally, comprises approximately 50% of the clinically severe β-thalassemia disorders.

• homozygotes - mild microcytic anaemia, hypochromic anaemia
• haemoglobin E/ßo thalassaemia, however, resembles homozygous ßo thalassaemia - haematologically and clinically

The haemoglobin level alone should not be the major factor in initiating transfusion. Rather, the broader picture should be considered with particular attention to growth failure, lack of activity, and the earlier appearance of skeletal change.

If it is clear that the patient requires regular transfusion the regimen to be followed, including chelation, is similar to that for the management of thalassemia major.

Patients who do not require regular transfusion should have serum ferritin or hepatic MRI estimations at least twice per year. Increased iron levels should be controlled by intermittent courses of chelating agents.

Reference

1. Weatherall D et al. The Haemoglobin E Thalassemias. Cold Spring Harb Perspect Med. 2012 Aug;2(8):a011734