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

Twenty-five individuals were studied from four unrelated Mexican Mestizo fa milies with Hb D-Los Angeles. We observed five compound heterozygotes: four for Hb S and Hb D, and one for Hb D and beta-thalassemia (beta degrees 39 nonsense mutation); 16 heterozygotes: four for Hb S, seven for Hb D, and fi ve for beta-thalassemia, while the remaining four were normal. The four Hb S/Hb D patients had severe hemolytic anemia, while in the Hb D/beta-thalass emia patient, the anemia was similar to that of a beta-thalassemia heterozy gote; therefore, Hb D is clinically harmful when it is associated with Hb S . The beta(S) chromosomes were associated with the Benin haplotype in two f amilies and Bantu in one family, while the beta(D) and beta(0) 39 mutations ,were associated with haplotype 1 [+ -----+ +]. The Bantu and Benin haploty pes have been found with high frequency in Db S individuals from the East C oast and Northwestern Mexico. The BD chromosomes from Italy were also shown to be associated with haplotype I, the most frequently observed haplotype in the world; there are no haplotype studies on beta(D) chromosomes from In dia or China where Hb D-Los Angeles is most common. Thus, the true origin o f this mutation observed in these Mestizo families remains to be elucidated .