CLINICAL AND GENETIC CHARACTERISTICS OF HbS_OMAN: A SEVERE UNREVEALED FORM OF SICKEL CELL DISEASE

HbS/SOman is a severe variant of sickle hemoglobinopathy that results from 2 simultaneous mutations in the same B globin gene. The first is the classic Bs mutation (B6 Gluandrarr;val) and the second is in position 121 (B121 Gluandrarr;lys). Previous reports explained that the carriers of this disease in Oman present in 2 different clinical syndromes: a) High expressors of HbSOman and concomitant andalpha;/andalpha;andalpha; thalassemia (expressing about 20% HbS/Oman) presenting in the heterozygote state with clinical manifestations of Sickle Cell Disease of varying severity. b) Low expressors of HbS/Oman with concomitant - andalpha;/-andalpha; thalassemia (expressing about 14% of HbSOman) who are asymptomatic. In the literature only 6 carriers have been described so far. Recently, in our OPD, we observed more carriers in presenting with severe forms. In addition, for the first time in Oman, we have identified for compound heterozygotes HbS/Oman who have presented an extremely severe clinical phenotype presenting as transfusion dependent thalassemia major presenting with hypersplenism and frequent blood transfusion from early infancy. This disease entity is not adequately described in the literature. There are many devastating consequences of a delay in diagnosing either heterozygotes the compound heterozygotes. The current study will be conducted to identify the magnitude of the problem in Oman, classify this disease, explain its genetics and its phenotype modifiers if any.