Concomitant inheritance of α‐thalassemia in β°‐thalassemia/hb e disease

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Abstract
Concomitant inheritance of α-thalassemia in patients with β°-thalassemia/hemoglobin (Hb) E disease was detected by restriction endonuclease DNA mapping. Among 42 patients with β°-thalassemia/Hb E disease, seven were found to have an α-thalassemia-2 haplotype. Of these, five belonged to the rightward or 3.7-kb type of α-thalassemia-2 and the remaining two the leftward or 4.2-kb type. All the seven patients with α-thalassemia-2 haplotype had hemoglobin levels of 7.4 g/dl or above; those without detectable α-thalassemia had hemoglobin levels both higher and lower than 7.4 g/dI. The latter attended the clinic regularly, the former did occasionally. These findings suggest that concomitant inheritance of α-thalassemia can alleviate the severity of β°-thalassemia/Hb E disease. Failure to find α-thalassemia-1 haplotype in these patients suggests that concomitant inheritance of α-thalassemia-1 with β°-thalassemia/Hb E might lead to so mild a condition that the individuals do not present clinically. The fact that many patients without a detectable α-thalassemia haplotype also had hemoglobin levels of 7.4 g/dl or higher suggests that there are additional factors responsible for the mildness of β°-thalassemia/Hb E disease.