A long noncoding RNA from the HBS1L-MYB intergenic region on chr6q23 regulates human fetal hemoglobin expression

Pharmacogenomics of Drugs Used in β-Thalassemia and Sickle-Cell Disease: From Basic Research to Clinical Applications

In this short review we have presented and discussed studies on pharmacogenomics (also termed pharmacogenetics) of the drugs employed in the treatment of β-thalassemia or Sickle-cell disease (SCD). This field of investigation is relevant, since it is expected to help clinicians select the appropriate drug and the correct dosage for each patient. We first discussed the search for DNA polymorphisms associated with a high expression of γ-globin genes and identified this using GWAS studies and CRISPR-based gene editing approaches. We then presented validated DNA polymorphisms associated with a high HbF production (including, but not limited to the HBG2 XmnI polymorphism and those related to the BCL11A, MYB, KLF-1, and LYAR genes). The expression of microRNAs involved in the regulation of γ-globin genes was also presented in the context of pharmacomiRNomics. Then, the pharmacogenomics of validated fetal hemoglobin inducers (hydroxyurea, butyrate and butyrate analogues, thalidomide, and sirolimus), of iron chelators, and of analgesics in the pain management of SCD patients were considered. Finally, we discuss current clinical trials, as well as international research networks focusing on clinical issues related to pharmacogenomics in hematological diseases.

Identification and characterization of CHD4-associated eRNA as a novel modulator of fetal hemoglobin levels in β-thalassemia

Fetal-to-adult hemoglobin switching is controlled by programmed silencing of γ-globin while the re-activation of fetal hemoglobin (HbF) is an effective strategy for ameliorating the clinical severity of β-thalassemia and sickle cell disease. The identification of enhancer RNAs (eRNAs) related to the fetal (α2γ2) to adult hemoglobin (α2β2) switching remains incomplete. In this study, the transcriptomes of GYPA+ cells from six β-thalassemia patients with extreme HbF levels were sequenced to identify differences in patterns of noncoding RNA expression. It is interesting that an enhancer upstream of CHD4, an HbF-related core subunit of the NuRD complex, was differentially transcribed. We found a significantly positive correlation of eRNA-CHD4 enhancer-gene interaction using the public database of FANTOM5. Specifically, the eRNA-CHD4 expression was found to be significantly higher in both CD34+ HSPCs and HUDEP-2 than those in K562 cells which commonly expressed high level of HbF, suggesting a correlation between eRNA and HbF expression. Furthermore, prediction of transcription binding sites of cis-eQTLs and the CHD4 genomic region revealed a putative interaction site between rs73264846 and ZNF410, a known transcription factor regulating HbF expression. Moreover, in-vitro validation showed that the inhibition of eRNA could reduce the expression of HBG expression in HUDEP-2 cells. Taken together, the findings of this study demonstrate that a distal enhancer contributes to stage-specific silencing of γ-globin genes through direct modulation of CHD4 expression and provide insights into the epigenetic mechanisms of NuRD-mediated hemoglobin switching.

Peripheral blood circular RNA circ-0008102 may serve as a novel clinical biomarker in beta-thalassemia patients

Circular RNA circ-0008102 has previously been found dysregulated in β-thalassemia (β-thal) in circRNAs microarray (GSE196682 and GSE241141). Our study is aimed at identifying whether circ-0008102 could be a novel biomarker in β-thal. The peripheral blood of pediatric β-thal patients with (n = 39) or without (n = 20) blood transfusion and healthy controls (n = 30) was selected. qRT-PCR, ROC curve analysis, Spearman correlation analysis, and FISH were used to analyze clinical value of circ-0008102. qRT-PCR confirmed that circ-0008102 expression in pediatric β-thal patients without blood transfusion was significantly higher. ROC curves analysis showed that the AUC of circ-0008102 for differentiating patients without blood transfusion from patients with blood transfusion and healthy controls with an AUC of 0.733 and 0.711. Furthermore, circ-0008102 expression was positively correlated with the levels of RBC, HbF, β-globin, and γ-globin mRNA, but was negatively corrected with the levels of HbA and Cr. circ-0008102 was mainly located in the cytoplasm. circ-0008102 could induce the activation of γ-globin and negatively regulate the expression of the five highest-ranking candidate miRNAs (miR-372-3p, miR-329-5p, miR-198, miR-152-5p, and miR-627-3p) in K562 cells.

CONCLUSION

We demonstrate that peripheral blood upregulated circ-0008102 may serve as a novel clinical biomarker for pediatric β-thal without blood transfusion.

WHAT IS KNOWN

• CircRNAs are known to be involved in various human diseases, and several circRNAs are regarded as a class of promising blood-based biomarkers for detection of β-thal. • CircRNAs exert biological functions by epigenetic modification and gene expression regulation, and dysregulated circRNAs in β-thal might be involved in the induction of HbF in β-thal.

WHAT IS NEW

• Peripheral blood circ-0008102 maybe serve as a novel clinical biomarker for detection of pediatric β-thal without blood transfusion. • Circ-0008102 participates in the pathogenesis of β-thal through regulating γ-globin expression, and negatively regulates the expression of miR-372-3p, miR-329-5p, miR-198, miR-152-5p and miR-627-3p.

Activation of γ-globin expression by LncRNA-mediated ERF promoter hypermethylation in β-thalassemia

The mechanism that drives the switch from fetal to adult hemoglobin (Hb) provides a therapeutic target for β-thalassemia. We have previously identified that hypermethylation of transcription factor ERF promoter reactivated γ-globin expression. To uncover the mechanism underlying the hypermethylation of ERF promoter, we performed RNA sequencing in β0/β0-thalassemia patients and identified an upregulated long noncoding RNA (RP11-196G18.23) associated with HbF production. RP11-196G18.23 bound to the ERF promoter and recruited DNA methyltransferase 3A to promote DNA hypermethylation-mediated ERF downregulation, thereby ameliorating ERF-induced γ-globin inactivation. The identification of RP11-196G18.23 provides an epigenetic mechanism for the reactivation of fetal γ-globin expression for β-hemoglobinopathies.

An enhancer RNA recruits MLL1 to regulate transcription of Myb

The Myb proto-oncogene encodes the transcription factor c-MYB, which is critical for hematopoiesis. Distant enhancers of Myb form a hub of interactions with the Myb promoter. We identified a long non-coding RNA (Myrlin) originating from the -81 kb murine Myb enhancer. Myrlin and Myb are coordinately regulated during erythroid differentiation. Myrlin TSS deletion using CRISPR/Cas9 reduced Myrlin and Myb expression and LDB1 complex occupancy at the Myb enhancers, compromising enhancer contacts and reducing RNA Pol II occupancy in the locus. In contrast, CRISPRi silencing of Myrlin left LDB1 and the Myb enhancer hub unperturbed, although Myrlin and Myb expression were downregulated, decoupling transcription and chromatin looping. Myrlin interacts with the MLL1 complex. Myrlin CRISPRi compromised MLL1 occupancy in the Myb locus, decreasing CDK9 and RNA Pol II binding and resulting in Pol II pausing in the Myb first exon/intron. Thus, Myrlin directly participates in activating Myb transcription by recruiting MLL1.

Non-coding RNAs in human health and disease: potential function as biomarkers and therapeutic targets

Human diseases have been a critical threat from the beginning of human history. Knowing the origin, course of action and treatment of any disease state is essential. A microscopic approach to the molecular field is a more coherent and accurate way to explore the mechanism, progression, and therapy with the introduction and evolution of technology than a macroscopic approach. Non-coding RNAs (ncRNAs) play increasingly important roles in detecting, developing, and treating all abnormalities related to physiology, pathology, genetics, epigenetics, cancer, and developmental diseases. Noncoding RNAs are becoming increasingly crucial as powerful, multipurpose regulators of all biological processes. Parallel to this, a rising amount of scientific information has revealed links between abnormal noncoding RNA expression and human disorders. Numerous non-coding transcripts with unknown functions have been found in addition to advancements in RNA-sequencing methods. Non-coding linear RNAs come in a variety of forms, including circular RNAs with a continuous closed loop (circRNA), long non-coding RNAs (lncRNA), and microRNAs (miRNA). This comprises specific information on their biogenesis, mode of action, physiological function, and significance concerning disease (such as cancer or cardiovascular diseases and others). This study review focuses on non-coding RNA as specific biomarkers and novel therapeutic targets.

Long Non-Coding RNA Prostate Cancer Non-Coding RNA 1/miR-211-5p/Death Effector Domain Containing 2 Axis Affects Preeclampsia by Modulating Trophoblast Cells Proliferation and Apoptosis

Background: Preeclampsia (PE) is a pregnancy-specific hypertensive disorder that affects 5–7% of pregnant women and is characterized by edema, hypertension and proteinuria. It is one of the leading causes of morbidity and mortality in pregnant women and newborns. Evidences reveal that the expression of long non-coding RNA (lncRNA) prostate cancer non-coding RNA 1 (PRNCR1) is abnormal in PE. Therefore, we investigated the role of lncRNA PRNCR1 in PE development and its molecular mechanism. Methods: Quantitative reverse transcription PCR (qRT-PCR) was used to determine the expression levels of lncRNA PRNCR1, microRNA (miR)-211-5p and mRNA leval of death effector domain containing 2 (DEDD2). Besides, the expression level of DEDD2 was detected by western blot assay. Cell proliferation ability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and cell apoptosis was detected by flow cytometry assay. Transwell assay was used to detect the migration and invasion of HTR-8/SVneo cells. The relationship between miR-211-5p and lncRNA PRNCR1 or DEDD2 was verified by dual luciferase reporter gene assay. Results: Over-expression of lncRNA PRNCR1 induced apoptosis, impeded proliferation, migration, invasion in HTR-8/SVneo cells. Knockdown of lncRNA PRNCR1 inhibited apoptosis, promoted cell proliferation, migration and invasion, and all these effects were offset by miR-211-5p inhibitor. The mRNA and protein levels of DEDD2 were decreased by overexpressing miR-211-5p in HTR-8/SVneo cells, while miR-211-5p inhibitor significantly increased the mRNA and protein levels of DEDD2. Conclusions: lncRNA PRNCR1 regulated cell behavior (proliferation, apoptosis, migration, and invasion) via the miR-211-5p/DEDD2 axis in HTR-8/SVneo cells. Thus, lncRNA PRNCR1 participated in the occurrence and development of PE.

Exploring the crosstalk between long non-coding RNAs and microRNAs to unravel potential prognostic and therapeutic biomarkers in β-thalassemia

β-thalassemia is a prevalent monogenic disorder characterized by reduced or absent synthesis of the β-globin chain. Although great effort has been made to ameliorate the disease severity of β-thalassemic patients, progress has been stymied due to limited understanding of the detailed molecular mechanism of disease pathogenesis. Recently, non-coding RNAs have been established as key players in regulating various physiological and pathological processes. Many ncRNAs are involved in hematopoiesis and erythroid development. Furthermore, various studies have also reported the complex interplay between different ncRNAs, such as miRNA, lncRNAs, etc. in regulating disease progression and pathogenesis. Both lncRNAs and miRNAs have been identified as independent regulators of globin gene expression and are intricately involved in disease pathogenesis; yet accumulating evidence suggests that the cross-talk between lncRNAs and miRNAs is intricately involved in the underlying globin gene expression, fine-tuning the effect of their independent regulation. In this review, we summarize the current progress of research on the roles of lncRNAs and miRNAs implicated in β-thalassemia disease, including their interactions and regulatory networks. This can provide important insights into the detailed epigenetic regulation of globin gene switching and has the potential to develop novel therapeutic approaches against β-thalassemia.

Targeting Genetic Modifiers of HBG Gene Expression in Sickle Cell Disease: The miRNA Option

Sickle cell disease (SCD) is one of the most common inherited hemoglobinopathy disorders that affects millions of people worldwide. Reactivation of HBG (HBG1, HBG2) gene expression and induction of fetal hemoglobin (HbF) is an important therapeutic strategy for ameliorating the clinical symptoms and severity of SCD. Hydroxyurea is the only US FDA-approved drug with proven efficacy to induce HbF in SCD patients, yet serious complications have been associated with its use. Over the last three decades, numerous additional pharmacological agents that reactivate HBG transcription in vitro have been investigated, but few have proceeded to FDA approval, with the exception of arginine butyrate and decitabine; however, neither drug met the requirements for routine clinical use due to difficulties with oral delivery and inability to achieve therapeutic levels. Thus, novel approaches that produce sufficient efficacy, specificity, and sustainable HbF induction with low adverse effects are desirable. More recently, microRNAs (miRNAs) have gained attention for their diagnostic and therapeutic potential to treat various diseases ranging from cancer to Alzheimer’s disease via targeting oncogenes and their gene products. Thus, it is plausible that miRNAs that target HBG regulatory genes may be useful for inducing HbF as a treatment for SCD. Our laboratory and others have documented the association of miRNAs with HBG activation or suppression via silencing transcriptional repressors and activators, respectively, of HBG expression. Herein, we review progress made in understanding molecular mechanisms of miRNA-mediated HBG regulation and discuss the extent to which molecular targets of HBG might be suitable prospects for development of SCD clinical therapy. Lastly, we discuss challenges with the application of miRNA delivery in vivo and provide potential strategies for overcoming barriers in the future.

Expression, functional mechanism and therapy application of long noncoding RNA in thalassemia

β-thalassemia (β-thal) is one of the most common genetic diseases in the world, its pathogenesis is extremely complex and there is no effective treatment at present. The birth of children with moderate and severe β-thal brings economic pressure to families, social medical and health services. Long noncoding RNA (lncRNA) is a type of noncoding protein transcripts with a length greater than 200 nucleotides, which is involved in a variety of biological processes, such as cell proliferation, differentiation and chromosome variation and plays an important role in the epigenetic and post-transcriptional regulation of genes. It has potential value in the diagnosis, prevention and treatment of β-thal. LncRNA possesses the characteristics such as tissue specificity, cell specificity, developmental stage specificity, space-time specificity and disease specificity, and its complex interaction network has become a challenge to translate research results into clinical practice. Taking lncRNA as an entry point, in-depth understanding of the function of lncRNA in β-thal and explanation of its related regulatory mechanisms will provide theoretical basis for targeting treatment of β-thal, which can improve the diagnosis and treatment of β-thal.

Comparison of transcriptome profiles of nucleated red blood cells in cord blood between preterm and full-term neonates

BACKGROUND

The reactivation of fetal γ-globin expression is an effective strategy for ameliorating the clinical symptoms of β-hemoglobinopathies. However, the mechanism of globin switching, especially the roles of long non-coding RNAs (lncRNAs) in this process, remains elusive.

METHODS

We compared the in vivo transcriptome profiles of nucleated red blood cells (NRBCs) isolated from the umbilical cord blood of preterm and full-term newborns. We collected 75 umbilical cord blood samples and performed qPCR of the candidate genes.

RESULTS

In this study, we identified 7,166 differentially expressed protein-coding genes, 3,243 differentially expressed lncRNAs, and 79 differentially expressed microRNAs. Our data show that the Fanconi anemia pathway and the H19/let-7/LIN28B axis may be involved in γ- to β-globin gene switching. Moreover, we constructed the hub gene network of the differentially expressed transcription factors. Based on qPCR, we found that BCL11A was differentially expressed based on biological sex. We also confirmed that H19 is differentially expressed and established the H19-related network to reveal the potential regulatory mechanisms.

CONCLUSION

We present the profiles of the in vivo transcriptome differences of NRBCs between preterm and full-term neonates for the first time, and provide novel research targets for β-hemoglobinopathies.

SEC23A rescues SEC23B-deficient congenital dyserythropoietic anemia type II

Congenital dyserythropoietic anemia type II (CDAII) results from loss-of-function mutations in SEC23B. In contrast to humans, SEC23B-deficient mice deletion do not exhibit CDAII but die perinatally with pancreatic degeneration. Here, we demonstrate that expression of the full SEC23A protein (the SEC23B paralog) from the endogenous regulatory elements of Sec23b completely rescues the SEC23B-deficient mouse phenotype. Consistent with these data, while mice with erythroid-specific deletion of either Sec23a or Sec23b do not exhibit CDAII, we now show that mice with erythroid-specific deletion of all four Sec23 alleles die in mid-embryogenesis with features of CDAII and that mice with deletion of three Sec23 alleles exhibit a milder erythroid defect. To test whether the functional overlap between the SEC23 paralogs is conserved in human erythroid cells, we generated SEC23B-deficient HUDEP-2 cells. Upon differentiation, these cells exhibited features of CDAII, which were rescued by increased expression of SEC23A, suggesting a novel therapeutic strategy for CDAII.

Molecular genetics of β-thalassemia: A narrative review

ABSTRACT

β-thalassemia is a hereditary hematological disease caused by over 350 mutations in the β-globin gene (HBB). Identifying the genetic variants affecting fetal hemoglobin (HbF) production combined with the α-globin genotype provides some prediction of disease severity for β-thalassemia. However, the generation of an additive composite genetic risk score predicts prognosis, and guide management requires a larger panel of genetic modifiers yet to be discovered.Presently, using data from prior clinical trials guides the design of further research and academic studies based on gene augmentation, while fundamental insights into globin switching and new technology developments have inspired the investigation of novel gene therapy approaches.Genetic studies have successfully characterized the causal variants and pathways involved in HbF regulation, providing novel therapeutic targets for HbF reactivation. In addition to these HBB mutation-independent strategies involving HbF synthesis de-repression, the expanding genome editing toolkit provides increased accuracy to HBB mutation-specific strategies encompassing adult hemoglobin restoration for personalized treatment of hemoglobinopathies. Allogeneic hematopoietic stem cell transplantation was, until very recently, the curative option available for patients with transfusion-dependent β-thalassemia. Gene therapy currently represents a novel therapeutic promise after many years of extensive preclinical research to optimize gene transfer protocols.We summarize the current state of developments in the molecular genetics of β-thalassemia over the last decade, including the mechanisms associated with ineffective erythropoiesis, which have also provided valid therapeutic targets, some of which have been shown as a proof-of-concept.

A novel lincRNA identified in buffalo oocytes with protein binding characteristics could hold the key for oocyte competence

Studying the maternal oocyte-specific genes, in farm animals is a significant step towards delineating the underlying mechanisms that regulate oocyte quality, early embryonic development and survival. With the creation of buffalo oocyte-specific subtracted cDNA library, it has raised new questions which need to be answered. The present study has characterized one of the ESTs selected from the library and highlighted its importance in the oocyte quality. The selected EST was made full length by RLM-RACE and four transcript variants were identified. Bioinformatics analysis indicated the novelty of full-length transcript along with conserved intergenic nature. The largest transcript was identified as long intergenic noncoding RNA based upon coding potential calculator output. The expression analysis at different hours of oocyte maturation showed a significant variation in developmentally competent oocytes to that of incompetent ones. Along with this, the transcript was also found to have protein binding ability which was confirmed by RNA electrophoretic mobility shift assay. The protein used in the experiment was isolated from oocyte and cumulus cells via sonication. A novel lincRNA has been reported here that might have an important role in maturation of oocytes, inferred from its relative gene expression study and protein binding characteristics.

Distinct miRNA Signatures and Networks Discern Fetal from Adult Erythroid Differentiation and Primary from Immortalized Erythroid Cells

MicroRNAs (miRNAs) are small non-coding RNAs crucial for post-transcriptional and translational regulation of cellular and developmental pathways. The study of miRNAs in erythropoiesis elucidates underlying regulatory mechanisms and facilitates related diagnostic and therapy development. Here, we used DNA Nanoball (DNB) small RNA sequencing to comprehensively characterize miRNAs in human erythroid cell cultures. Based on primary human peripheral-blood-derived CD34+ (hCD34+) cells and two influential erythroid cell lines with adult and fetal hemoglobin expression patterns, HUDEP-2 and HUDEP-1, respectively, our study links differential miRNA expression to erythroid differentiation, cell type, and hemoglobin expression profile. Sequencing results validated by reverse-transcription quantitative PCR (RT-qPCR) of selected miRNAs indicate shared differentiation signatures in primary and immortalized cells, characterized by reduced overall miRNA expression and reciprocal expression increases for individual lineage-specific miRNAs in late-stage erythropoiesis. Despite the high similarity of same-stage hCD34+ and HUDEP-2 cells, differential expression of several miRNAs highlighted informative discrepancies between both cell types. Moreover, a comparison between HUDEP-2 and HUDEP-1 cells displayed changes in miRNAs, transcription factors (TFs), target genes, and pathways associated with globin switching. In resulting TF-miRNA co-regulatory networks, major therapeutically relevant regulators of globin expression were targeted by many co-expressed miRNAs, outlining intricate combinatorial miRNA regulation of globin expression in erythroid cells.

Long noncoding RNA HBBP1 enhances γ-globin expression through the ETS transcription factor ELK1

β-Thalassemia is an autosomal recessive genetic disease caused by defects in the production of adult hemoglobin (HbA, α₂β₂), which leads to an imbalance between α- and non-α-globin chains. Reactivation of γ-globin expression is an effective strategy to treat β-thalassemia patients. Previously, it was demonstrated that hemoglobin subunit beta pseudogene 1 (HBBP1) is associated with elevated fetal hemoglobin (HbF, α₂γ₂) in β-thalassemia patients. However, the mechanism underlying HBBP1-mediated HbF production is unknown. In this study, using bioinformatics analysis, we found that HBBP1 is involved in γ-globin production, and then preliminarily confirmed this finding in K562 cells. When HBBP1 was overexpressed, γ-globin expression was increased at the transcript and protein levels in HUDEP-2 cells. Next, we found that ETS transcription factor ELK1 (ELK1) binds to the HBBP1 proximal promoter and significantly promotes its activity. Moreover, the synthesis of γ-globin was enhanced when ELK1 was overexpressed in HUDEP-2 cells. Surprisingly, ELK1 also directly bound to and activated the γ-globin proximal promoter. Furthermore, we found that HBBP1 and ELK1 can interact with each other in HUDEP-2 cells. Collectively, these findings suggest that HBBP1 can induce γ-globin by enhancing ELK1 expression, providing some clues for γ-globin reactivation in β-thalassemia.

Direct Generation of Immortalized Erythroid Progenitor Cell Lines from Peripheral Blood Mononuclear Cells

Reliable human erythroid progenitor cell (EPC) lines that can differentiate to the later stages of erythropoiesis are important cellular models for studying molecular mechanisms of human erythropoiesis in normal and pathological conditions. Two immortalized erythroid progenitor cells (iEPCs), HUDEP-2 and BEL-A, generated from CD34+ hematopoietic progenitors by the doxycycline (dox) inducible expression of human papillomavirus E6 and E7 (HEE) genes, are currently being used extensively to study transcriptional regulation of human erythropoiesis and identify novel therapeutic targets for red cell diseases. However, the generation of iEPCs from patients with red cell diseases is challenging as obtaining a sufficient number of CD34+ cells require bone marrow aspiration or their mobilization to peripheral blood using drugs. This study established a protocol for culturing early-stage EPCs from peripheral blood (PB) and their immortalization by expressing HEE genes. We generated two iEPCs, PBiEPC-1 and PBiEPC-2, from the peripheral blood mononuclear cells (PBMNCs) of two healthy donors. These cell lines showed stable doubling times with the properties of erythroid progenitors. PBiEPC-1 showed robust terminal differentiation with high enucleation efficiency, and it could be successfully gene manipulated by gene knockdown and knockout strategies with high efficiencies without affecting its differentiation. This protocol is suitable for generating a bank of iEPCs from patients with rare red cell genetic disorders for studying disease mechanisms and drug discovery.

Genome-Wide Transcriptional Regulation of the Long Non-coding RNA Steroid Receptor RNA Activator in Human Erythroblasts

Erythropoiesis of human hematopoietic stem cells (HSCs) maintains generation of red blood cells throughout life. However, little is known how human erythropoiesis is regulated by long non-coding RNAs (lncRNAs). By using ChIRP-seq, we report here that the lncRNA steroid receptor RNA activator (SRA) occupies chromatin, and co-localizes with CTCF, H3K4me3, and H3K27me3 genome-wide in human erythroblast cell line K562. CTCF binding sites that are also occupied by SRA are enriched for either H3K4me3 or H3K27me3. Transcriptome-wide analyses reveal that SRA facilitates expression of erythroid-associated genes, while repressing leukocyte-associated genes in both K562 and CD36-positive primary human proerythroblasts derived from HSCs. We find that SRA-regulated genes are enriched by both CTCF and SRA bindings. Further, silencing of SRA decreases expression of the erythroid-specific markers TFRC and GYPA, and down-regulates expression of globin genes in both K562 and human proerythroblast cells. Taken together, our findings establish that the lncRNA SRA occupies chromatin, and promotes transcription of erythroid genes, therefore facilitating human erythroid transcriptional program.

Association of HMIP1 C-893A polymorphism and disease severity in patients with sickle cell anemia

Introduction

Sickle cell anemia (SCA) is a Mendelian disorder with a heterogeneous clinical course. The reasons for this phenotypic diversity are not entirely established, but it is known that high fetal hemoglobin levels lead to a milder course of the disease. Additionally, genetic variants in the intergenic region HBS1L-MYB promote high levels of fetal hemoglobin into adulthood.

Objective

In the present study, we investigated the HMIP1 C-839A (rs9376092) polymorphism, located at the HBS1L-MYB intergenic region block 1, in SCA patients.

Method

We analyzed 299 SCA patients followed in two reference centers in Brazil. The HMIP1 C-839A (rs9376092) genotypes were determined by allele specific polymerase chain reactions. Clinical and laboratory data were obtained from patient interviews and medical records.

Results

The median fetal hemoglobin levels were higher in patients with the HMIP1 C-839A (rs9376092) AA genotype (CC = 6.4%, CA = 5.6% and AA = 8.6%), but this difference did not reach significance (p = 0.194). No association between HMIP1 C-839A (rs9376092) genotypes and other clinical and laboratorial features was detected (p > 0.05).

Conclusion

In summary, our data could not support the previously related association between the HMIP1 C-893A (rs9376092) polymorphism and differential fetal hemoglobin levels.

Sickle cell disease in the era of precision medicine: looking to the future

Introduction

Sickle cell anemia is a mendelian disease that is noted for the heterogeneity of its clinical expression. Because of this, providing an accurate prognosis has been a longtime quest.

Areas covered

Reviewed are the benefits and shortcomings of testing for the major modulators of the severity of disease, like fetal hemoglobin and α thalassemia, along with studies that have attempted to link genetic variation with sub-phenotypes of disease in a predictive fashion. Induced pluripotent stem cells driven to differentiate into erythroid precursor cells provide another area for potential patient-specific drug testing.

Expert opinion

Fetal hemoglobin is the strongest modulator of sickle cell anemia but simply measuring its blood levels is an insufficient means of forecasting an individual's prognosis. A more precise method would be to know the distribution of fetal hemoglobin levels across the population of red cells, an assay not yet available. Prognostic measures have been developed using genetic and other signatures, but their predictive value is suboptimal. Widely applicable assays must be developed to allow a tailored approach to using the several new treatments that are likely to be available in the near future.

MicroRNAs and Long Non-coding RNAs in Genetic Diseases

Since the discovery and classification of non-coding RNAs, their roles have gained great attention. In this respect, microRNAs and long non-coding RNAs have been firmly demonstrated to be linked to regulation of gene expression and onset of human diseases, including rare genetic diseases; therefore they are suitable targets for therapeutic intervention. This issue, in the context of rare genetic diseases, is being considered by an increasing number of research groups and is of key interest to the health community. In the case of rare genetic diseases, the possibility of developing personalized therapy in precision medicine has attracted the attention of researchers and clinicians involved in developing "orphan medicinal products" and proposing these to the European Medicines Agency (EMA) and to the Food and Drug Administration (FDA) Office of Orphan Products Development (OOPD) in the United States. The major focuses of these activities are the evaluation and development of products (drugs, biologics, devices, or medical foods) considered to be promising for diagnosis and/or treatment of rare diseases or conditions, including rare genetic diseases. In an increasing number of rare genetic diseases, analysis of microRNAs and long non-coding RNAs has been proven a promising strategy. These diseases include, but are not limited to, Duchenne muscular dystrophy, cystic fibrosis, Rett syndrome, and β-thalassemia. In conclusion, a large number of approaches based on targeting microRNAs and long non-coding RNAs are expected in the field of molecular diagnosis and therapy, with a facilitated technological transfer in the case of rare genetic diseases, in virtue of the existing regulation concerning these diseases.

MYB - A regulatory factor in hematopoiesis

MYB is a transcription factor which was identified in birds as a viral oncogene (v-MYB). Its cellular counterpart was subsequently isolated as c-MYB which has three functional domains - DNA binding domain, transactivation domain and negative regulatory domain. c-MYB is essential for survival, and deletion of both alleles of the gene results in embryonic death. It is highly expressed in hematopoietic cells, thymus and neural tissue, and required for T and B lymphocyte development and erythroid maturation. Additionally, aberrant MYB expression has been found in numerous solid cancer cells and human leukemia. Recent studies have also implicated c-MYB in the regulation of expression of fetal hemoglobin which is highly beneficial to the β-hemoglobinopathies (beta thalassemia and sickle cell disease). These findings suggest that MYB could be a potential therapeutic target in leukemia, and possibly also a target for therapeutic increase of fetal hemoglobin in the β-hemoglobinopathies.