Hb Chile [beta 28(B10)Leu -> Met]: an unstable hemoglobin associated with chronic methemoglobinemia and sulfonamide or methylene blue-induced hemolytic anemia

Among the causes of life-long cyanosis are congenital methemoglobinemia due to M hemoglobins, congenital methemoglobinemia due to methemoglobin reduct ase deficiency, a small number of low oxygen affinity hemoglobins, and a sm all number of unstable hemoglobins that spontaneously form methemoglobin in vivo at an accelerated rate. We report an unstable hemoglobin with these c haracteristics that was observed in a family of indigenous (native American ) origin living near Santiago, Chile. This variant has the substitution bet a 28(B10)Leu --> Met, unambiguously corresponding to the DNA mutation of (C ) under bar TG -->(A) under bar TG in beta-globin gene codon 28.