Hb D-Los Angeles Associated with Hb S or β-Thalassemia in Four Mexican Mestizo Families

Abstract

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 β-thalassemia (β⁰ 39 nonsense mutation); 16 heterozygotes: four for Hb S, seven for Hb D, and five for β-thalassemia, while the remaining four were normal. The four Hb S/Hb D patients had severe hemolytic anemia, while in the Hb D/β-thalassemia patient, the anemia was similar to that of a β-thalassemia heterozygote; therefore, Hb D is clinically harmful when it is associated with Hb S. The β^S chromosomes were associated with the Benin haplotype in two families and Bantu in one family, while the β^D and β⁰ 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 β^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 β^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.