RESUMO
Glucose-6-phosphate dehydrogenase (G6PD) deficiency has previously been reported among both the black and white populations of Costa Rica. All 28 G6PD A- samples were found to be of the common G6PD A-376G/202A type. A previously described mutation associated with nonspherocytic hemolytic anemia, G6PD Puerto Limón, was found to be due to a G----A transition at nucleotide (nt) 1192, causing a glu----lys substitution. Mutations in this region of the G6PD molecule seem invariably to be associated with chronic hemolytic anemia. G6PD Santamaria had been described previously in two unrelated white subjects. We found that both did, indeed, have the same mutations. In this variant the A----G substitution at nt 376 that is characteristic of G6PD A was present, but an A----T mutation at nt 542, apparently superimposed on the ancient G6PD A mutation, resulted in an asp----val substitution. Thus, the gain of a negative charge at amino acid 126 was counterbalanced by the loss of a charge at amino acid 181, giving rise to a variant with the G6PD A mutation but with normal electrophoretic mobility.
Assuntos
Deficiência de Glucosefosfato Desidrogenase/genética , Glucosefosfato Desidrogenase/genética , Isoenzimas/genética , Mutação , População Negra/genética , Costa Rica , Análise Mutacional de DNA , Humanos , Masculino , População Branca/genéticaRESUMO
Glucose-6-phosphate dehydrogenase (G6PD) deficiency appears to be fairly common in Mexico. We have now examined the DNA of three previously reported electrophoretically fast Mexican G6PD variants, -G6PD Distrito Federal, G6PD Tepic, and G6PD Castilla. All three of these variants, believed on the basis of biochemical characterization and population origin to be unique, have the G----A transition at nucleotide 202 and the A----G transition at nucleotide 376, mutations that we now recognize to be characteristic of G6PD A-. Two other Mexican males with G6PD deficiency were found to have the same mutation. All five have the (NlaIII/FokI/PvuII/PstI) haplotype characteristic of G6PD A -in Africa. Since the PvuII+ genotype seems to be rare in Europe, we conclude that all of these G6PD A - genes had their ancient origin in Africa, although in many of the Mexican patients with G6PD A -202A/376G the gene may have been imported more recently from Spain, where this variant, formerly known as G6PD Betica, is also prevalent.