Summary Sickle cell disease (SCD) in Saudi patients from the Eastern Province is associated with the Arab-Indian (AI) HBB (β-globin gene) haplotype. The phenotype of AI SCD in children was described as benign and was attributed to their high fetal haemoglobin (HbF). We conducted a hospital-based study to assess the pattern of SCD complications in adults. A total of 104 patients with average age of 27 years were enrolled. Ninety-six percent of these patients reported history of painful crisis; 47% had at least one episode of acute chest syndrome, however, only 15% had two or more episodes; symptomatic osteonecrosis was reported in 18%; priapism in 17%; overt stroke in 6%; none had leg ulcers. The majority of patients had persistent splenomegaly and 66% had gallstones. Half of the patients co-inherited α-thalassaemia and about one third had glucose-6-phosphate dehydrogenase deficiency. Higher HbF correlated with higher rate of splenic sequestration but not with other phenotypes. The phenotype of adult patients with AI SCD is not benign despite their relatively high HbF level. This is probably due to the continued decline in HbF level in adults and the heterocellular and variable distribution of HbF amongst F-cells.
Sickle cell anemia is common in the Middle East and India where the HbS gene is sometimes associated with the Arab-Indian (AI) β-globin gene (HBB) cluster haplotype. In this haplotype of sickle cell anemia, fetal hemoglobin (HbF) levels are 3-4 fold higher than those found in patients with HbS haplotypes of African origin. Little is known about the genetic elements that modulate HbF in AI haplotype patients. We therefor studied Saudi HbS homozygotes with the AI haplotype (mean HbF 19.2±7.0%, range 3.6 to 39.6%) and known genotyped cis- and trans-acting elements associated with HbF expression. All cases, regardless of HbF concentration, were homozygous for AI haplotype-specific elements cis to HBB. SNPs in BCL11A and HBS1L-MYB that were associated with HbF in other populations explained only 8.8% of the variation of HbF. KLF1 polymorphisms associated previously with high HbF were not present In the 44 patients tested. The SNPs and genetic loci we have chosen for this study do not explain the high HbF in sickle cell patients with AI haplotype or its variation among patients with this haplotype. The dispersion of HbF levels among AI haplotype patients suggests that other genetic elements modulate the effects of the known cis- and trans-acting regulators. These regulatory elements, which remain to be discovered, might be specific in the Saudi and some other populations where HbF levels are especially high.
Background Fetal hemoglobin (HbF) levels in sickle cell anemia patients vary. We genotyped polymorphisms in the erythroid-specific enhancer of BCL11A to see if they might account for the very high HbF associated with the Arab-Indian (AI) haplotype and Benin haplotype of sickle cell anemia. Methods and Results Six BCL112A enhancer SNPs and their haplotypes were studied in Saudi Arabs from the Eastern Province and Indian patients with AI haplotype (HbF ~20%), African Americans (HbF ~7%), and Saudi Arabs from the Southwestern Province (HbF ~12%). Four SNPs (rs1427407, rs6706648, rs6738440, and rs7606173) and their haplotypes were consistently associated with HbF levels. The distributions of haplotypes differ in the 3 cohorts but not their genetic effects: the haplotype TCAG was associated with the lowest HbF level and the haplotype GTAC was associated with the highest HbF level and differences in HbF levels between carriers of these haplotypes in all cohorts was approximately 6%. Conclusions Common HbF BCL11A enhancer haplotypes in patients with African origin and AI sickle cell anemia have similar effects on HbF but they do not explain their differences in HbF.
Allogeneic HSCT is the only curative treatment for SCD. In this study, we estimated the number of Saudi patients with SCD who are candidates for HSCT. We used the presence of overt stroke, recurrent ACS, and frequent severe pain crisis as indications for HSCT. We calculated the frequencies of these complications among a Saudi SCD cohort of 376 patients with SCD, 250 from SW and 126 from Eastern (E) provinces. We found that 59 (23.6%) of SW patients were transplant candidates compared to 22 (17.4%) from E province. It is estimated that about 61 000 patients with SCD live in Saudi Arabia. Thus, the projected number of Saudi patients with SCD who are candidates for HSCT is 10 536 patients. Of those, 2148 are children. The burden of SCD on HSCT centers in Saudi Arabia is substantial and is difficult currently to meet the demand. We recommend recruiting/training more transplant physicians and nurses, expand current capacity of centers if feasible, and open new transplant centers to make HSCT a practical therapeutic option for patients with severe SCD in Saudi Arabia.
IntroductionHigh white blood cell (WBC) count is an indicator of sickle cell disease (SCD) severity, however, there are limited studies on WBC counts in Saudi Arabian patients with SCD. The aim of this study was to estimate the prevalence of abnormal leukocyte count (either low or high) and identify factors associated with high WBC counts in a sample of Saudi patients with SCD.MethodsA cross-sectional and retrospective chart review study was carried out on 290 SCD patients who were routinely treated at King Fahad Hospital in Hofuf, Saudi Arabia. An interview was conducted to assess clinical presentations, and we reviewed patient charts to collect data on blood test parameters for the previous 6 months.ResultsAlmost half (131 [45.2%]) of the sample had abnormal leukocyte counts: low WBC counts 15 (5.2%) and high 116 (40%). High WBC counts were associated with shortness of breath (P=0.022), tiredness (P=0.039), swelling in hands/feet (P=0.020), and back pain (P=0.007). The mean hemoglobin was higher in patients with normal WBC counts (P=0.024), while the mean hemoglobin S was high in patients with high WBC counts (P=0.003). After adjustment for potential confounders, predictors of high WBC counts were male gender (adjusted odds ratio [aOR]=3.63) and patients with cough (aOR=2.18), low hemoglobin (aOR=0.76), and low heart rate (aOR=0.97).ConclusionAbnormal leukocyte count was common: approximately five in ten Saudi SCD patients assessed in this sample. Male gender, cough, low hemoglobin, and low heart rate were associated with high WBC count. Strategies targeting high WBC count could prevent disease complication and thus could be beneficial for SCD patients.
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