Hb D-Los Angeles associated with Hb S or ?-thalassemia in four Mexican Mestizo families

Twenty-five individuals were studied from four unrelated Mexican Mestizo families with Hb D-Los Angeles. We observed five compound heterozygotes: four for Hb S and Hb D, and one for Hb D and ?-thalassemia (?0 39 nonsense mutation); 16 heterozygotes: four for Hb S, seven for Hb D, and five for ?- thalassemia, while the remaining four were normal. The four Hb S/Hb D patients had severe hemolytic anemia, while in the Hb D/?-thalassemia patient, the anemia was similar to that of a ?-thalassemia heterozygote; therefore, Hb D is clinically harmful when it is associated with Hb S. The ?(S) chromosomes were associated with the Benin haplotype in two families and Bantu in one family, while the ?(D) and ?0 39 mutations were associated with haplotype 1 [+ - - - - + +]. The Bantu and Benin haplotypes have been found with high frequency in Hb S individuals from the East Coast and Northwestern Mexico. The ?(D) chromosomes from Italy were also shown to be associated with haplotype 1, the most frequently observed haplotype in the world; there are no haplotype studies on ?(D) chromosomes from India or China where Hb D-Los Angeles is most common. Thus, the true origin of this mutation observed in these Mestizo families remains to be elucidated