Abstract: | This paper describes the case of a 6-year-old Saudi male who had sickle cell heterozygosity, beta +-thalassaemia and possessed three alpha-genes of the haplotype alpha alpha alpha anti-3.7/as diagnosed by restriction endonuclease studies using Hpa I, Bam HI, Bgl II, Hind III and Xba I. Since the iron level was found to be normal, it is proposed that the coexistence of beta-thalassaemia with triple alpha-genes in Hb S heterozygotes may be the cause of the anemia. A possible mechanism for severe anaemia is presented. |