Avaliação eletroforética, cromatográfica e molecular da Hb D Los Angeles no Brasil

Abstract

The most common Hb D variant, the Hb D-Los Angeles, also know as Hb D-Punjab, originates through a GAA®CAA change at the 121 codon of the b globin gene; this mutation results in the replacement of glutamic acid for glutamine in the protein. It is the third most common hemoglobin variant in the Brazilian population. This variant has electrophoretic migration in alkaline pHs similar to Hb S and identical migration to hemoglobin A in acidic pHs. Thus, several techniques are necessary for its correct diagnosis. The purpose of this work was to relate the different laboratorial techniques and molecular analyses to determine the profile of Hb D Los Angeles in Brazil. Forty-seven individuals from the Brazilian population with Hb D Los Angeles were studied. Multiple electrophoresis in several experimental conditions were carried out, in addition to high performance liquid chromatography (HPLC) and molecular analysis to confirm this mutation. Four compound heterozygotes were observed: 42 individuals heterozygous Hb AD Los Angeles, two with Hb S/D Los Angeles disease, two individuals with Hb D Los Angeles and beta-thalassemia and one with Hb D Los Angeles and Hb Lepore. The heterozygous hemoglobin D Los Angeles is asymptomatic, even though its association with other variants and thalassemias may present varying degrees of clinical manifestations. The results presented emphasize the significance of the association of different laboratorial techniques for D Los Angeles diagnosis, and help to elucidate rare combinations.