has causal or contributing genetic variation Hemoglobin Barts Additional info from the definition in HPO: "Hb Barts (Hemoglobin Barts) is a tetramer with four gamma globin chains, and is essentially pathognomonic for one or another form of alpha thalassemia. Hb Barts has an extremely high affinity for oxygen, resulting in almost no oxygen delivery to the tissues." Hb Bart's HP:0005507 Suggest update to description in HP as we have done. An abnormal hemoglobin, composed of four gamma globin chains, causing it to have an extremely high affinity for oxygen, resulting in almost no oxygen delivery to the tissues. Haemoglobin Barts Suggest update to description Hemoglobin Bart's http://purl.obolibrary.org/obo/HP_0005507 Haemoglobin Bart's Hb Barts Homozygous Deletion of HBA1 and HBA2 Abnormal Hemoglobin