The beta-globin genotype E121Q/W15X (cd121GAA -> CAA/cd15TGG -> TGA) underlines Hb D/beta-(0) thalassaemia marked by domination of haemoglobin D

Among 13,525 haemoglobin analyses performed in our laboratory we detected 2 1 cases of haemoglobin D (Hb D) disease. Investigation of a family affected with this abnormal haemoglobin revealed two cases of Hb D/beta-(0) thalass aemia for the first time among Saudi Arabs. The two patients were diagnosed as having chronic haemolytic anaemia of moderate severity on the basis of the haemoglobin level. haematocrit, mean corpuscular haemoglobin, mean corp uscular volume, reticulocyte count, red blood cell count microscopy, elevat ed serum conjugated and non-conjugated bilirubin, increased serum lactic de hydrogenase, and the occasional need for blood transfusions. Genetic analys is enabled the detection of compound heterozygosity for the missense E121Q (codon 121 GAA-->CAA) and stop W15X (codon 15 TGG-->TGA) mutations as causa tive of the clinical phenotype of Hb D-LosAngeles (Punjab)/beta-(0) thalass aemia. The disease manifested as domination of Hb D and moderate haemolytic anaemia. The co-inheritance of beta-(0) thalassaemia seems to be responsib le for conferring the deleterious effect on the presentation of Hb D diseas e in these patients. The present result emphasizes the significance of mole cular testing in resolving certain diagnostic ambiguities in haematology as in cases of heterozygous Hb D in association with beta-(0) thalassaemia wh ich, by haemoglobin electrophoresis, may be misdiagnosed as Hb D homozygosi ty.