title: Hb Johnstown [beta109(G11)Val-->Leu]: A high oxygen affinity variant associated with beta0-thalassemia.
abstract: Hb Johnstown [beta109(G11)Val-->Leu], a high oxygen affinity hemoglobin (Hb) variant associated with beta0-thalassemia (thal) [IVS-I-1 (G-->A)], was identified in an 8-year-old girl referred to our laboratory because of erythrocytosis and a left-shifted oxygen dissociation curve (ODC). The phylogenetic tree showed that the mother was heterozygous for the Hb variant and the father was a beta0-thal carrier. This Hb variant, with normal electrophoresis, was characterized at the DNA level by beta gene sequencing. The amino acid substitution potentially disrupts alpha1beta1 contacts i n the deoxyHb conformation, thus shifting the equilibrium towards the high affinity oxyHb conformation. The erythrocytosis and low values for actual P50 due to Hb Johnstown were more marked due to the co-inheritance of the beta0-thal.
authors.affiliation: Servicio de Hematología-Oncología, Hospital de Pediatría Professor Dr Juan P Garrahan, Buenos Aires, Argentina. afeliutorres@yahoo.com
authors.forename: Aurora
authors.initials: A
authors.lastname: Feliu-Torres
authors.forename: Silvia Eandi
authors.initials: SE
authors.lastname: Eberle
authors.forename: Ariel
authors.initials: A
authors.lastname: Roldán
authors.forename: Silvia
authors.initials: S
authors.lastname: González
authors.forename: Gabriela
authors.initials: G
authors.lastname: Sciuccati
mesh_terms: D002648:Child; D005260:Female; D006455:Hemoglobins, Abnormal / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D010100:Oxygen / Q000378:metabolism*; D010290:Parents; D011086:Polycythemia / Q000150:complications / Q000378:metabolism; D017086:beta-Thalassemia / Q000150:complications / Q000235:genetics* / Q000378:metabolism
chemical_list: D006455:Hemoglobins, Abnormal; C066866:hemoglobin Johnstown; D010100:Oxygen