Functional polymorphisms of BCL11A and HBS1L-MYB genes affect both fetal hemoglobin level and clinical outcomes in a cohort of children with sickle cell anemia.
- 作者列表："Sales RR","Belisário AR","Faria G","Mendes F","Luizon MR","Viana MB
:Fetal hemoglobin (HbF) ameliorates clinical severity of sickle cell anemia (SCA). The major loci regulating HbF levels are HBB cluster, BCL11A, and HMIP-2 (HBS1L-MYB). However, the impact of noncoding single-nucleotide polymorphisms (SNPs) in these loci on clinical outcomes and their functional role on regulating HbF levels should be better elucidated. Therefore, we performed comprehensive association analyses of 14 noncoding SNPs in five loci with HbF levels and with clinical outcomes in a cohort of 250 children with SCA from Southeastern Brazil, and further performed functional annotation of these SNPs. We found SNPs independently associated with HbF levels: rs4671393 in BCL11A (β-coefficient = 0.28), rs9399137 in HMIP-2A (β-coefficient = 0.16), and rs4895441 in HMIP-2B (β-coefficient = 0.15). Patients carrying minor (HbF-boosting) alleles for rs1427407, rs93979137, rs4895441, rs9402686, and rs9494145 showed reduced count of reticulocytes (p < 0.01), while those carrying the T allele of rs9494145 showed lower white blood cell count (p = 0.002). Carriers of the minor allele for rs9402686 showed higher peripheral saturation of oxygen (p = 0.002). Patients carrying minor alleles in BCL11A showed lower risk of transfusion incidence rate ratio (IRR ≥ 1.3; p < 0.0001). This effect was independent of HbF effect (p = 0.005). Carriers of minor alleles for rs9399137 and rs9402686 showed lower risk of acute chest syndrome (IRR > 1.3; p ≤ 0.01). Carriers of the reference allele for rs4671393 showed lower risk of infections (IRR = 1.16; p = 0.01). In conclusion, patients carrying HbF-boosting alleles of BCL11A and HMIP-2 were associated with milder clinical phenotypes. Higher HbF concentration may underlie this effect.
: 胎儿血红蛋白 (HbF) 改善镰状细胞性贫血 (SCA) 的临床严重程度。调节HbF水平的主要基因座是HBB簇、BCL11A和HMIP-2 (HBS1L-MYB)。然而，应该更好地阐明这些位点中的非编码单核苷酸多态性 (snp) 对临床结果的影响及其在调节HbF水平上的功能作用。因此，我们在来自巴西东南部的250名SCA儿童队列中，对5个位点的14个非编码SNPs与HbF水平和临床结局进行了综合关联分析，并进一步对这些SNPs进行了功能注释.我们发现SNPs与HbF水平独立相关: BCL11A中的rs4671393 (β 系数 = 0.28)，HMIP-2A中的rs9399137 (β 系数 = 0.16)，HMIP-2B中的rs4895441 (β 系数 = 0.15)。携带rs1427407、rs93979137、rs4895441、rs9402686和rs9494145次要 (HbF-boosting) 等位基因的患者显示网织红细胞计数减少 (p <0.01)，而携带rs9494145 T等位基因的患者显示白细胞计数较低 (p = 0.002)。rs9402686次要等位基因的携带者显示更高的外周氧饱和度 (p = 0.002)。BCL11A中携带次要等位基因的患者输血发生率比的风险较低 (IRR ≥ 1.3; p <0.0001)。该效应独立于HbF效应 (p = 0.005)。rs9399137和rs9402686次要等位基因携带者患急性胸部综合征的风险较低 (IRR > 1.3; p ≤ 0.01)。rs4671393参考等位基因的携带者显示较低的感染风险 (IRR = 1.16; p = 0.01)。总之，携带BCL11A和HMIP-2的HbF增强等位基因的患者与较温和的临床表型相关。较高的HbF浓度可能是该效应的基础。
METHODS:BACKGROUND:Thalassemia is one of the most common monogenetic diseases in the south of China and Southeast Asia. Hemoglobin Bart's hydrops fetalis syndrome was caused by a homozygous Southeast Asian deletion (-/-) in the HBA gene. Few studies have proved the potential of screen for Bart's hydrops fetalis using fetal cell-free DNA. However, the number of cases is still relatively small. Clinical trials of large samples would be needed. OBJECTIVE:In this study, we aimed to develop a noninvasive method of target-captured sequencing and genotyping by the Bayesian method using cell-free fetal DNA to identify the fetal genotype in pregnant women who are at risk of having hemoglobin Bart hydrops fetalis in a large-scale study. STUDY DESIGN:In total, 192,173 couples from 30 hospitals were enrolled in our study and 878 couples were recruited, among whom both the pregnant women and their husbands were detected to be carriers of Southeast Asian type (-/αα) of α-thalassemia. Prenatal diagnosis was performed by chorionic villus sampling, amniocentesis, or cordocentesis using gap-polymerase chain reaction considered as the golden standard. RESULTS:As a result, we found that the sensitivity and specificity of our noninvasive method were 98.81% and 94.72%, respectively, in the training set as well as 100% and 99.31%, respectively, in the testing set. Moreover, our method could identify all of 885 maternal samples with the Southeast Asian carrier and 36 trisomy samples with 100% of sensitivity in T13, T18, and T21 and 99.89% (1 of 917) and 99.88% (1 of 888) of specificity in T18 and T21, respectively. CONCLUSION:Our method opens the possibility of early screening for maternal genotyping of α-thalassemia, fetal aneuploidies in chromosomes 13/18/21, and hemoglobin Bart hydrops fetalis detection in 1 tube of maternal plasma.
METHODS:OBJECTIVES:Sickle cell disease (SCD) is a serious illness with disabling acute and chronic pain that needs better therapies, but insufficient patient participation in research is a major impediment to advancing SCD pain management. The purpose of this article is to discuss the challenges of conducting an SCD study and approaches to successfully overcoming those challenges. DESIGN:In a repeated-measures, longitudinal study designed to characterize SCD pain phenotypes, we recruited 311 adults of African ancestry. Adults with SCD completed 4 study visits 6 months apart, and age- and gender-matched healthy controls completed 1 visit. RESULTS:We recruited and completed measures on 186 patients with SCD and 125 healthy controls. We retained 151 patients with SCD with data at 4 time points over 18 months and 125 healthy controls (1 time point) but encountered many challenges in recruitment and study visit completion. Enrollment delays often arose from patients' difficulty in taking time from their complicated lives and frequent pain episodes. Once scheduled, participants with SCD cancelled 49% of visits often because of pain; controls canceled 30% of their scheduled visits. To facilitate recruitment and retention, we implemented a number of strategies that were invaluable in our success. CONCLUSION:Patients' struggles with illness, chronic pain, and their life situations resulted in many challenges to recruitment and completion of study visits. Important to overcoming challenges was gaining the trust of patients with SCD and a participant-centered approach. Early identification of potential problems allowed strategies to be instituted proactively, leading to success.
METHODS:OBJECTIVES:Sickle cell anemia is the commonest genetic disorder in India, and the frequency of the sickle cell gene is very high in the remote tribal areas where facilities are generally limited. Therefore, a rapid and affordable point-of-care test for sickle cell disease is needed. METHODS:The diagnostic accuracy of HemoTypeSC was evaluated against automated high-performance liquid chromatography (HPLC) as the gold standard for its efficacy in a newborn screening program. RESULTS:A total of 1,559 individuals (980 newborns and 579 adults) from four participating centers were analyzed by both methods. HemoTypeSC correctly identified 209 of 211 total hemoglobin (Hb) SS cases, for a 99.1%/99.9% total HbSS sensitivity/specificity. Overall, HemoTypeSC exhibited sensitivity and specificity of 98.1% and 99.1% for all possible phenotypes (HbAA, HbAS, and HbSS) detected. HPLC is relatively expensive and not available in most laboratories in remote tribal areas. CONCLUSIONS:We conclude that the rapid, point-of-care testing device HemoTypeSC test is suitable for population and newborn screening for the HbS phenotype.