has causal or contributing genetic variation HBB, GLU6VAL HBB, GLU121LYS Hemoglobin S-Oman SCDO (Jade Hotchkiss) Hb S-Oman Request inclusion into the HPO, below "Abnormal Hemoglobin"/"Sickling Hemoglobin with Two Beta-Globin Gene Substitutions". Negligable Hemoglobin S (Oman) A form of hemoglobin caused by two mutations in a beta-globin chain, the classic beta S mutation (beta6 Glu> Val) and a beta121 Glu > Lys mutation identical to that of Hb-O Arab. The hemoglobin variant has reduced solubility and there is an apparent increase in red cell sickling tendency. It is reported to cause a rare dominant form of sickle cell disease, Sickle Cell Disease A/S-Oman. Nagel, R.L., Daar, S., Romero, J.R., Suzuka, S.M., Gravell, D., Bouhassira, E., Schwartz, R.S., Fabry, M.E. and Krishnamoorthy, R., 1998. HbS-Oman heterozygote: a new dominant sickle syndrome. Blood, 92(11), pp.4375-4382. Sickling Hemoglobin with Two Beta-Globin Gene Substitutions