Natural history of sickle hemoglobinopathies in Omani children

Purpose. Sickle hemoglobinopathies as described in neighbouring countries exhibits a wide spectrum of clinical behaviour. In Oman, however, its clinical course has never been characterized and therefore a study of the natural history of sickle cell disease was undertaken. Patients and Methods. Using retrospective review of case notes, a total of 375 Omani children, aged between 3 months and 16 years were studied. The severity index for each patient was calculated from a total score of 12 clinical and laboratory variables. All the cases were diagnosed using a high performance liquid chromatography technique and level of hemoglobin A2 was determined using elution method. Seventy six cases of homozygous SCA were haplotyped. Fifty of them were mapped for presence or absence of Alpha Thalassemia trait. Results and Conclusions. A total of 157 cases (41.9%) were diagnosed before the age of one year. The severity index correlated well with the age of diagnosis (P<.005). More than two thirds (66%) of our cases were running a mild course of the disease. The majority of the patients (61.2%) were homozygous sickle cell anemia followed by double heterozygous types mainly sickle cell β thalassemia. African Haplotypes were predominant (68.53%) and 80% of those screened for α globin gene mutations were heterozygous or homozygous for α-Thalassemia 2. There was no significant correlation between phenotype and haplotype forms and the severity of the disease. About half of the patients had splenomegaly and preserved splenic function which may relate to the low incidence of infections observed in our patients compared to other reports. There was low documentation of acute chest syndrome and cerebrovascular accidents compared to published data. Other complications are comparable to other studies. Factors possibly influencing the severity of the disease are discussed. The most likely association is the presence of alpha thalassemia gene mutation and high Hb F levels(P≤.01). The results were compared with those of other countries.