A strategy to detect beta-thalassaemia minor

Over the past three years 25 302 adults in Kentucky have been tested for haemoglobinopathies, and of these, haemoglobin A2 was measured on 3734, 1973 with microcytosis and 1761 within the normal range. The best methods of detecting beta-thalassaemia minor using red-blood-cell indices were compared. No method detected all heterozygotes. A new method was devised consisting of three parts: (1) haemoglobin electrophoresis, (2) calculation of the product of the square of the mean corpuscular volume (M.C.V.) multiplied by the mean corpuscular haemoglobin (M.C.H.) measured in units of one hundred, (3) A2 determination on all AA samples with (M.C.V.)2 X M.C.H. less than 1530 and on those with variant genotypes consistent with thalassaemia. In this series this new method detected 137 out of 138 heterozygotes with 4-4% false-positives.