has causal or contributing genetic variation Reduced Alpha/Gamma Synthesis Ratio Absence of Alpha Globin Synthesis with Gamma Globin Synthesis SCDO (Clair Ingram) None The state, in utero or shortly after birth, in which all four alpha globin genes are deleted or inactivated resulting in absent alpha globin synthesis. If gamma globin synthesis persists, then the resulting phenotype is hemoglobin Barts (four gamma chains) and hemoglobin Bart hydrops fetalis. Request inclusion into HPO below "Reduced Alpha/Gamma Synthesis Ratio" (also requested for inclusion). Marengo-Rowe, A.J., 2007, January. The thalassemias and related disorders. In Baylor university medical center proceedings (Vol. 20, No. 1, pp. 27-31). Taylor & Francis. Homozygous Deletion of HBA1 and HBA2