The effect of alpha-thalassemia on the level of hybrid hemoglobin variants in heterozygotes

Clinical course and molecular characterization of a compound heterozygote for sickle hemoglobin and hemoglobin Kenya

We describe a 25-year-old black woman who presented with a long history of anemia requiring transfusions during childhood and adolescence. Molecular analysis revealed her to be a compound heterozygote for the sickle mutation and the approximately 22.7 kb deletion associated with hemoglobin Kenya. This patient's clinical course was more severe than previously reported for the Hb S/Hb Kenya genotype, a probable consequence of concomitant iron deficiency.

The beta-delta crossover leading to the beta delta hybrid gene of hemoglobin P-Nilotic is located within 54 base-pairs of the 5' end of exon 2 or between codons 31 and 50

The crossover region of the beta delta hybrid gene of the hemoglobin variant Hb P-Nilotic was defined in detail through cloning and sequencing of appropriate DNA segments. The crossover must have occurred without loss of bases within a 54 base-pair stretch of DNA between bases 275 and 330 (or between amino acid residues 31 and 50), indicating that the exon 1 and IVS-1 originate from beta, and exon 2, IVS-2 and exon 3 from delta. The data support the speculation that the IVS-1, in contrast to IVS-2, has no effect on the expression of this hybrid gene.