RESUMO
Unstable hemoglobins are structural variants of the hemoglobin molecule, mostly originated by single amino-acid replacement in some globin chains. These changes affect molecule stability, leading to loss of solubility, precipitation, and cellular lysis. Patients carrying these unstable hemoglobins may present mild to severe chronic hemolytic anemia. Hemoglobin Evans is an unstable variant originated by replacement of valine with methionine at position 62 of the α-globin chain. We have identified this variant in a girl with an acute hemolytic crisis associated to pharyngitis, as well as in two of her family members. This is the third case of hemolytic anemia due to hemoglobin Evans reported in the literature.
Assuntos
Anemia Hemolítica/genética , Hemoglobinas Anormais , Argentina , Criança , Feminino , HumanosRESUMO
Las hemoglobinas inestables son variantes estructurales de lamolécula de hemoglobina originadas, en su mayoría, por sustitucionespuntuales de aminoácidos en alguna de las cadenas de globina. Estos cambios afectan la estabilidad de la molécula,causan pérdida de la solubilidad y precipitación dentro del eritrocito, lo cual provoca su destrucción acelerada. Desde el punto de vista clínico, las hemoglobinas inestables puedenpresentar anemia hemolítica crónica de gravedad variable.La hemoglobina Evans es una hemoglobina inestable causadapor la sustitución de valina por metionina en la posición 62 de la cadena de alfa globina. Hemos identificado esta variante en una niña con crisis hemolítica aguda asociada a faringitis y en dos miembros de su grupo familiar. Éste es el tercer caso de anemia hemolítica congénita causada por hemoglobina Evans comunicado en la bibliografía mundial.
Unstable hemoglobins are structural variants of the hemoglobin molecule, mostly originated by single amino-acid replacement in some globin chains. These changes affect molecule stability, leading to loss of solubility, precipitation, and cellular lysis. Patients carrying these unstable hemoglobins may present mild to severe chronic hemolytic anemia. Hemoglobin Evans is an unstable variant originated by replacement of valine with methionine at position 62 of the αa-globin chain. We have identified this variant in a girl with an acute hemolytic crisis associated to pharyngitis, as well as in two of her family members. This is the third case of hemolytic anemia due to hemoglobin Evans reported in the literature.
