Gene correction of HBB mutations in CD34+ hematopoietic stem cells using Cas9 mRNA and ssODN donors

Background

β-Thalassemia is an inherited hematological disorder caused by mutations in the human hemoglobin beta (HBB) gene that reduce or abrogate β-globin expression. Although lentiviral-mediated expression of β-globin and autologous transplantation is a promising therapeutic approach, the risk of insertional mutagenesis or low transgene expression is apparent. However, targeted gene correction of HBB mutations with programmable nucleases such as CRISPR/Cas9, TALENs, and ZFNs with non-viral repair templates ensures a higher safety profile and endogenous expression control.

Methods

We have compared three different gene-editing tools (CRISPR/Cas9, TALENs, and ZFNs) for their targeting efficiency of the HBB gene locus. As a proof of concept, we studied the personalized gene-correction therapy for a common β-thalassemia splicing variant HBB^IVS1–110 using Cas9 mRNA and several optimally designed single-stranded oligonucleotide (ssODN) donors in K562 and CD34⁺ hematopoietic stem cells (HSCs).

Results

Our results exhibited that indel frequency of CRISPR/Cas9 was superior to TALENs and ZFNs (P < 0.0001). Our designed sgRNA targeting the site of HBB^IVS1–110 mutation showed indels in both K562 cells (up to 77%) and CD34⁺ hematopoietic stem cells—HSCs (up to 87%). The absolute quantification by next-generation sequencing showed that up to 8% site-specific insertion of the NheI tag was achieved using Cas9 mRNA and a chemically modified ssODN in CD34⁺ HSCs.

Conclusion

Our approach provides guidance on non-viral gene correction in CD34⁺ HSCs using Cas9 mRNA and chemically modified ssODN. However, further optimization is needed to increase the homology directed repair (HDR) to attain a real clinical benefit for β-thalassemia.

Electronic supplementary material

The online version of this article (10.1186/s40348-018-0086-1) contains supplementary material, which is available to authorized users.

A hit deconstruction approach for the discovery of fetal hemoglobin inducers

Beta-hemoglobinopathies such as sickle cell disease represent a major global unmet medical need. De-repression of fetal hemoglobin in erythrocytes is a clinically validated approach for the management of sickle cell disease, but the only FDA-approved medicine for this purpose has limitations to its use. We conducted a phenotypic screen in human erythroid progenitor cells to identify molecules with the ability to de-repress fetal hemoglobin, which resulted in the identification of the benzoxaborole-containing hit compound 1. This compound was found to have modest cellular potency and lead-like pharmacokinetics, but no identifiable SAR to enable optimization. Systematic deconstruction of a closely related analog of 1 revealed the fragment-like carboxylic acid 12, which was then optimized to provide tetrazole 31, which had approximately 100-fold improved cellular potency compared to 1, high levels of oral exposure in rats, and excellent solubility.

Elevated levels of platelet- and red cell-derived extracellular vesicles in transfusion-dependent β-thalassemia/HbE patients with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a serious complication in β-thalassemia. The mechanism of PAH development is believed to be through chronic platelet activation and red cell (RBC) membrane abnormality contributing to a hypercoagulable state and thrombosis, which consequently leads to the development of PAH. Extracellular vesicles (EVs) shed from the plasma membrane of platelets and RBCs are found to be associated with thrombotic risk. This study aimed to investigate the involvement of phosphatidylserine (PS)-bearing cells and EVs in accelerating the progression of the hypercoagulable state in transfusion-dependent thalassemia (TDT) patients. Fresh whole blood samples from splenectomized TDT-β-thalassemia/HbE patients (11 with PAH and 14 without PAH) and 15 normal subjects were analyzed for platelet activation by measuring P-selectin expression using flow cytometry and the number of dense granular using an electron microscope. The amounts of PS-bearing RBCs, large RBC-EVs, platelets, and medium EVs were determined by flow cytometry. Platelet activation in PAH patients was not significantly different from other groups; however, the amounts of PS-bearing large RBC-EVs, platelets, and medium platelet-derived EVs were significantly increased in PAH patients as compared to normal subjects, but they were not different from patients without PAH. This could be affected by antiplatelet therapy that reduced the levels of platelet activation and the amount of PS-bearing cells, including EVs, in PAH patients as well as in patients without PAH.

The survival rate of patients with beta-thalassemia major and intermedia and its trends in recent years in Iran

OBJECTIVES

Thalassemia is a common genetic disease in Iran, especially in the north and south of Iran. The present study sought to determine the survival rate of patients with thalassemia in highly endemic regions of Iran and its variation in patients born before and after 1971.

METHODS

The present historical cohort study extracted data from the health records of patients with beta-thalassemia major, beta-thalassemia intermedia, and sickle beta-thalassemia who had presented to thalassemia treatment centers in the past years. The collected data were analyzed using the Kaplan-Meier test, the log-rank test, and the chi-square test.

RESULTS

Of the total of 5,491 medical records (2,647 men and 2,634 women; mean age, 23.81±11.32 years), 3,936 belonged to patients with beta-thalassemia major, and 999 and 89 to patients with beta-thalassemia intermedia and sickle beta-thalassemia, respectively. In 467 cases, the type of thalassemia was not clear. The cumulative survival rate was calculated as 0.92, 0.83, 0.74, and 0.51 by ages 25, 35, 45, and 55, respectively. The hazard ratio of death was 4.22 (p<0.05) for beta-thalassemia major and 0.77 for beta-thalassemia intermedia (p=0.70). It was calculated as 1.45 for men patients and as 3.82 for single patients.

CONCLUSIONS

The present study showed relatively high survival rates in patients with thalassemia. The survival of patients was unfavorable in poorer regions (Zahedan and Iranshahr). Factors including women gender, a higher level of education, being married, and living in metropolises decreased the risk of death at younger ages and improved survival.

Dual-Energy X-ray Absorptiometry Predictors of Vertebral Deformities in Beta-Thalassemia Major

Vertebral fractures in beta-thalassemia major are increasingly found because of the longer life expectancy of patients, with a major negative impact on their quality of life. We performed a retrospective cross-sectional study to investigate the prevalence of vertebral deformities in thalassemic patients and to identify their best dual-energy X-ray absorptiometry (DXA) predictor among trabecular bone score (TBS), bone mineral density (BMD), and Z-score. Eighty-two outpatients with beta-thalassemia major on regular conventional treatment were studied at a single academic center. All patients underwent plain thoracic-lumbar spine X-rays and lumbar DXA to assess the number and the severity of vertebral deformities (Genant's method), the spinal deformity index, lumbar spine DXA parameters (BMD, TBS, and Z-score), and the presence of platyspondyly. Twenty-nine patients (35%) had vertebral deformities and showed significantly lower TBSs than the remainders (1.141 ± 0.083 vs 1.254 ± 0.072, p < 0.0001). The analysis of variance of the TBS between the group of patients without vertebral deformities (spinal deformity index = 0) and the remaining groups showed a significant difference (p < 0.001). The TBS had better sensitivity (86.2%), specificity (75.5%), and diagnostic accuracy (79.3%) than BMD and Z-score in discriminating patients with and without vertebral deformities. Combining the TBS with the BMD or the Z-score showed that the diagnostic accuracy of the first in discriminating patients with and without vertebral deformities improved from 79.3% to 85.4% and 87.8%, respectively. The presence of platyspondyly was a significant predictor of vertebral deformities in the multivariate model. Vertebral deformities in well-treated patients with beta-thalassemia major are common and are often unrecognized. In our hands, the TBS was better than the BMD and the Z-score in predicting vertebral deformities. Plain X-rays of the spine should be performed also in asymptomatic patients, especially when the TBS is low.

Outcome of Pregnancy with Hemoglobinopathy in a Tertiary Care Center

Purpose

The objective was to observe the characteristics among pregnant patients with a diagnosed hemoglobinopathy and to study the obstetric and medical morbidity patterns during the antenatal and the perinatal periods in this group of patients.

Methods

A prospective observational study was conducted in a tertiary care center.

Results

Sixty patients were studied in 11 months. Primigravidae (43.3%) formed the highest percentage of patients. β Thalassemia trait was the most common hemoglobinopathy, seen in 81.66% of study subjects. The hemoglobin value ranged from 5.7 to 13.0, with an average of 9.2 g/dl. Thyroid problems were the most common associated medical disorder. Though IUGR and placenta previa were common, there were no major obstetric problems. There were 57 live births and 1 fresh stillbirth. Two patients had spontaneous abortion for which uterine curettage was done. LSCS was the most common obstetric outcome. Patients with sickle-cell disease required more blood transfusion than those with beta-thalassemia trait. There were 2 maternal mortalities, and both the patients were the diagnosed cases of sickle-cell disease.

Conclusions

While the perinatal outcomes among women with sickle-cell disease are poor, the outcomes in pregnant patients with beta-thalassemia trait were not a cause of major concern.

The sensitive detection of IVSII-1(G˃A) mutation in beta globin gene using a Nano-based ligation genotyping system

Beta-thalassemia (β-thalassemia) is a globally genetic diseases, and is most prevalent in the Middle East, particularly in Iran. Carrier detection and prenatal diagnosis are the best ways to managing it, and to prevent new community cases from emerging. We report on a simple method for rapid detection of the worst β-thalassemia point mutation in Iran (IVS-II-1 G>A), using a nano-based ligation assay, this was performed using probes with labeled magnetic nanoparticles and quantum dots. After optimizing the technique, 50 DNA samples were genotyped with this method. We found a frequency of 72% for IVSII-1 (G˃A) mutation (42% heterozygote, and 30% mutant homozygote) with a highly sensitive nano-based ligation genotyping system, offering excellent sensitivity and specificity for point mutation detection; it has been demonstrated to be inaccurate, sensitive, cost-effective, and rapid technique for single nucleotide polymorphism (SNP) genotyping.

Modelling human haemoglobin switching

Genetic lesions of the β-globin gene result in haemoglobinopathies such as β-thalassemia and sickle cell disease. To discover and test new molecular medicines for β-haemoglobinopathies, cell-based and animal models are now being widely utilised. However, multiple in vitro and in vivo models are required due to the complex structure and regulatory mechanisms of the human globin gene locus, subtle species-specific differences in blood cell development, and the influence of epigenetic factors. Advances in genome sequencing, gene editing, and precision medicine have enabled the first generation of molecular therapies aimed at reactivating, repairing, or replacing silenced or damaged globin genes. Here we compare and contrast current animal and cell-based models, highlighting their complementary strengths, reflecting on how they have informed the scope and direction of the field, and describing some of the novel molecular and precision medicines currently under development or in clinical trial.

Blood rheology in children with the S/β+-thalassemia syndrome

The aim of the present study was to compare blood rheological parameters between children with homozygous sickle cell disease (SS), sickle cell SC disease or S/β+-thalassemia syndrome, and healthy children (AA) and to test the associations between blood rheology and the clinical severity in S/β+-thalassemia. Sixty-two SS, 14 SC, 11 S/β+-thalassemia and 12 healthy children participated in this study. Blood viscosity was measured with a cone-plate viscometer at 225 s-1. Red blood cell (RBC) deformability was measured by ektacytometry and RBC aggregation, by syllectometry. Nitric oxide and nitrotyrosine levels were determined for each child. While most of the hematological parameters were not different between SC and S/β+-thalassemia children, we demonstrated that SC patients had lower RBC deformability and aggregation than S/β+ individuals. Nitrotyrosine level, which indicates peroxynitrite production, was similar and lower in both healthy and S/β+ compared to SS children. However, S/β+-thalassemia children who experienced vaso-occlusive crises (VOC) in the 2 previous years had lower NOx and higher nitrotyrosine levels than those who never had VOC within the same period. These findings suggest that vascular function could be impaired in the most severe S/β+-thalassemia children compared to the less severe one.

[Clinical analysis of three cases with beta-thalassemia]

Objective: To study the diagnostic strategy of β-thalassemia through retrospective analysis of 3 cases of β-thalassemia. Methods: Three patients were admitted to the Department of Pediatrics, Sun Yat-sen Memorial Hospital of Sun Yat-sen University from January 2014 to June 2015. The clinical manifestations, hemoglobin electrophoresis and gene detection of these patients and their parents were analyzed, diagnostic ideas and key points were discussed when beta thalassemia gene detection did not explain clinical manifestations or hemoglobin electrophoresis. Results: Case 1, boy, 5 years old, was diagnosed as compound heterozygotes of β41-42 and IVS-Ⅱ-654 with hereditary persistence of fetal hemoglobin(HPFH) according to the clinical manifestations of mild anemia, normal size of liver and spleen, 92.8% fetal hemoglobin (HbF) and gene analysis. Case 2, girl, 3 years old, was confirmed the diagnosis of thalassemia intermedia with β41-42 heterozygote compound and ααα^anti3.7 heterozygote in accordance with the manifestations of severe anemia, hepatosplenomegaly, 8.6% HbF, 4.1% hemoglobin A₂(HbA₂) and gene analysis. Case 3, girl, 3 years old, with severe anemia, hepatosplenomegaly, 51.2% HbF and 3.7% HbA₂, was diagnosed as thalassemia major with compound heterozygotes of PolyA (T→C) and β17 by DNA sequencing. Conclusion: The diagnosis of β-thalassemia should be confirmed by clinical manifestations of hemolytic anemia, hemoglobin electrophoresis, gene diagnosis and family survey.

Monogenic diseases in India

Studies on monogenic diseases are considered valuable because they give insights and expand our knowledge on gene function and regulation. Despite all the current advancement in science and technology, a deep understanding and knowledge as to why only those particular genes are affected in a disease is still vague. We also lack profound illumination as to why only certain mutations are seen in a disease. Though useful from a research perspective, a majority of these diseases are lethal resulting in death of the affected individual. Unfortunately, in the fast - growing land of India, the incidence of monogenic diseases is very high with few counter-measures in place. This article encompasses a list of all monogenic diseases ever to be reported in India with special focus on five diseases which has been stated to have the highest incidence in India. Here, we discuss about the limited research carried out in India on these high incidence monogenic diseases, the other diseases related to those genes, the range of treatments available for these diseases in India in contrast to its availability around the world and the need to develop treatment strategies to reduce the mortality and morbidity due to these rare but daunting diseases.

[The effect of DNA hydroxymethylase Tet2 on γ globin activation in the treatment of β-thalassemia]

Objective: To study the function of ten-eleven translocation 2 (Tet2) in γ globin gene expression in patients with β- thalassemia. Methods: Gamma globin expression was induced by 5-azacytidine and Tet2 gene expression was knocked down by short hairpin RNA (shRNA) in a human immortalized myelogenous leukemia K562 cell line. The global 5-hydroxymethylcytosine (5hmC) level was measured by an ELISA kit. 5hmC level of γ globin gene was quantified by sulfite sequencing. The mRNA level of Tet2, γ globin, and related transcription factors Nfe4 and Klf1 were quantified by real-time PCR. Results: Tet2 knockdown resulted in a decreased global 5hmC level from 0.14% to 0.03% as of the control group in K562 cells. The expression of γ globin was enhanced after 5-azacytidine treatment in vitro. However, γ globin mRNA level in Tet2 knockdown cells was only 55% as that in control group. The CG sites on γ globin gene were unmethylated. As Tet2 was down-regulated, the expression levels of Nfe4 and Klf1 decreased by about 80% and increased to 3.5 folds, respectively. Conclusions: Tet2 appears to maintain 5hmC level and facilitates γ globin gene activation. Moreover, Tet2 more likely regulates γ globin expression via affecting transcription factors rather than the gene itself. Thus, Tet2 could be a potential therapeutic target for β thalassemias.

High resolution melting curve analysis targeting the HBB gene mutational hot-spot offers a reliable screening approach for all common as well as most of the rare beta-globin gene mutations in Bangladesh

BACKGROUND

Bangladesh lies in the global thalassemia belt, which has a defined mutational hot-spot in the beta-globin gene. The high carrier frequencies of beta-thalassemia trait and hemoglobin E-trait in Bangladesh necessitate a reliable DNA-based carrier screening approach that could supplement the use of hematological and electrophoretic indices to overcome the barriers of carrier screening. With this view in mind, the study aimed to establish a high resolution melting (HRM) curve-based rapid and reliable mutation screening method targeting the mutational hot-spot of South Asian and Southeast Asian countries that encompasses exon-1 (c.1 - c.92), intron-1 (c.92 + 1 - c.92 + 130) and a portion of exon-2 (c.93 - c.217) of the HBB gene which harbors more than 95% of mutant alleles responsible for beta-thalassemia in Bangladesh.

RESULTS

Our HRM approach could successfully differentiate ten beta-globin gene mutations, namely c.79G > A, c.92 + 5G > C, c.126_129delCTTT, c.27_28insG, c.46delT, c.47G > A, c.92G > C, c.92 + 130G > C, c.126delC and c.135delC in heterozygous states from the wild type alleles, implying the significance of the approach for carrier screening as the first three of these mutations account for ~85% of total mutant alleles in Bangladesh. Moreover, different combinations of compound heterozygous mutations were found to generate melt curves that were distinct from the wild type alleles and from one another. Based on the findings, sixteen reference samples were run in parallel to 41 unknown specimens to perform direct genotyping of the beta-thalassemia specimens using HRM. The HRM-based genotyping of the unknown specimens showed 100% consistency with the sequencing result.

CONCLUSIONS

Targeting the mutational hot-spot, the HRM approach could be successfully applied for screening of beta-thalassemia carriers in Bangladesh as well as in other countries of South Asia and Southeast Asia. The approach could be a useful supplement of hematological and electrophortic indices in order to avoid false positive and false negative results.

Haplotypes inside the beta-globin gene: use as new biomarkers for beta-thalassemia prenatal diagnosis in north of Iran

Background

Beta-thalassemia is common in the Mediterranean area as well as the Middle East and India. Official report in Iran revealed the average prevalence rate of carriers about 4%. More than 20 restriction fragment length polymorphisms (RFLPs) are known in the beta-globin gene cluster and used in the prenatal diagnosis (PND) services. Some of these locations may have low allele frequency and are not informative in the prenatal diagnosis. The current study aims to find new haplotypes and polymorphisms with high allele frequency in the local population.

Methods

Two thousand three hundred fifty samples (1,321 male and 1,029 female) from the northern Iran, whom suspected to be the carriers either for alpha or beta thalassemia and referred to the local diagnostic laboratory as a routine services were investigated during five years, (2010–2015). The beta-globin gene was sequenced for all samples.

Results

Heterozygosity for five SNPs in the beta-globin gene was calculated separately. 383 individuals (16.29%) showed no sign of nucleotide change in the beta-globin gene sequence. In total, codon2 (C/T) 31.72%, IVSII-16 (C/G) 31.72%, IVSII-74 (G/T) 54.71%, IVSII-81 (C/T) 19.47%, and IVSII-666 (T/C) 31.72% were seen respectively. Although all five polymorphisms showed reasonably high heterozygosity, IVSII-74 (G/T) [GG wild type (36.5%), G/T (54.71%) and TT (8.8%)] revealed the highest heterozygosity rate. Four combinations of these five SNPs were defined as new haplotypes named M1 to M4. ARMS-PCR also were designed and applied to detect IVSII-74 (G/T) nucleotide position.

Conclusions

This study represents an intragenic polymorphism, IVSII-74, a reliable position with high heterozygosity rates in Iranian population for PND analysis.

Trial registration

Retrospectively registered.

Carotid Doppler ultrasonography as a screening tool of early atherosclerotic changes in children and young adults with β-thalassemia major

PURPOSE

β-thalassemia major (β-TM) patients had an increased incidence of cardiovascular complications secondary to iron overload. They showed early carotid atherosclerosis as showed by increased carotid intima media thickness (CIMT) that may occur early even when significant iron overload is absent. We aimed to test the diagnostic performance of CIMT measurement by Doppler ultrasonography as a structural indicator for premature atherosclerosis in β-TM patients.

METHODS

Case-control study included 42 β-TM patients (24 males and 18 females) aged from 3 to 30 years and 36 age- and sex-matched healthy controls. Carotid Duplex was used for measurement of CIMT in all subjects.

RESULTS

The frequency of abnormal CIMT among patients was 19%. Mean CIMT of right anterior wall was 0.8 ± 0.16 (range 0.5-1.2) mm, of right posterior wall was 0.80 ± 0.17 (range 0.5-1.2), of right lateral wall was 0.8 ± 0.17 (range 0.5-1.1) mm. CIMT of left anterior wall ranged from 0.5 to 1.2 with mean 0.81 ± 0.17, CIMT of left posterior wall ranged from 0.5 to 1.1 with mean 0.80 ± 0.17 mm. Mean CIMT of left lateral wall was 0.81 ± 0.18 mm (range 0.5-1.2). CIMT of right anterior, right posterior and left anterior walls were thicker in patients compared to controls (P = 0.003, 0.015, < 0.001, respectively). There was no observable difference in CIMT between males and females, splenectomised and non-splenectomised, or well and poorly chelated subgroups (P > 0.05). CIMT of right lateral wall correlated with the disease duration (r = 0.3, P = 0.04).

CONCLUSIONS

Carotid ultrasound was a useful tool to detect subclinical atherosclerosis thorough CIMT evaluation in B-thalassemia major patients. B-thalassemia major children proved to have an increased CIMT regardless the state of iron overload.

A Universal Approach to Correct Various HBB Gene Mutations in Human Stem Cells for Gene Therapy of Beta-Thalassemia and Sickle Cell Disease

Beta-thalassemia is one of the most common recessive genetic diseases, caused by mutations in the HBB gene. Over 200 different types of mutations in the HBB gene containing three exons have been identified in patients with β-thalassemia (β-thal) whereas a homozygous mutation in exon 1 causes sickle cell disease (SCD). Novel therapeutic strategies to permanently correct the HBB mutation in stem cells that are able to expand and differentiate into erythrocytes producing corrected HBB proteins are highly desirable. Genome editing aided by CRISPR/Cas9 and other site-specific engineered nucleases offers promise to precisely correct a genetic mutation in the native genome without alterations in other parts of the human genome. Although making a sequence-specific nuclease to enhance correction of a specific HBB mutation by homology-directed repair (HDR) is becoming straightforward, targeting various HBB mutations of β-thal is still challenging because individual guide RNA as well as a donor DNA template for HDR of each type of HBB gene mutation have to be selected and validated. Using human induced pluripotent stem cells (iPSCs) from two β-thal patients with different HBB gene mutations, we devised and tested a universal strategy to achieve targeted insertion of the HBB cDNA in exon 1 of HBB gene using Cas9 and two validated guide RNAs. We observed that HBB protein production was restored in erythrocytes derived from iPSCs of two patients. This strategy of restoring functional HBB gene expression will be able to correct most types of HBB gene mutations in β-thal and SCD. Stem Cells Translational Medicine 2018;7:87-97.

Whole transcriptome analysis of human erythropoietic cells during ontogenesis suggests a role of VEGFA gene as modulator of fetal hemoglobin and pharmacogenomic biomarker of treatment response to hydroxyurea in β-type hemoglobinopathy patients

BACKGROUND

Human erythropoiesis is characterized by distinct gene expression profiles at various developmental stages. Previous studies suggest that fetal-to-adult hemoglobin switch is regulated by a complex mechanism, in which many key players still remain unknown. Here, we report our findings from whole transcriptome analysis of erythroid cells, isolated from erythroid tissues at various developmental stages in an effort to identify distinct molecular signatures of each erythroid tissue.

RESULTS

From our in-depth data analysis, pathway analysis, and text mining, we opted to focus on the VEGFA gene, given its gene expression characteristics. Selected VEGFA genomic variants, identified through linkage disequilibrium analysis, were explored further for their association with elevated fetal hemoglobin levels in β-type hemoglobinopathy patients. Our downstream analysis of non-transfusion-dependent β-thalassemia patients, β-thalassemia major patients, compound heterozygous sickle cell disease/β-thalassemia patients receiving hydroxyurea as fetal hemoglobin augmentation treatment, and non-thalassemic individuals indicated that VEGFA genomic variants were associated with disease severity in β-thalassemia patients and hydroxyurea treatment efficacy in SCD/β-thalassemia compound heterozygous patients.

CONCLUSIONS

Our findings suggest that VEGFA may act as a modifier gene of human globin gene expression and, at the same time, serve as a genomic biomarker in β-type hemoglobinopathy disease severity and hydroxyurea treatment efficacy.

High-resolution melting analysis for prenatal diagnosis of beta-thalassemia in northern Thailand

High-resolution melting (HRM) analysis is a rapid mutation analysis which assesses the pattern of reduction of fluorescence signal after subjecting the amplified PCR product with saturated fluorescence dye to an increasing temperature. We used HRM analysis for prenatal diagnosis of beta-thalassemia disease in northern Thailand. Five PCR-HRM protocols were used to detect point mutations in five different segments of the beta-globin gene, and one protocol to detect the 3.4 kb beta-globin deletion. We sought to characterize the mutations in carriers and to enable prenatal diagnosis in 126 couples at risk of having a fetus with beta-thalassemia disease. The protocols identified 18 common mutations causing beta-thalassemia, including the rare codon 132 (A-T) mutation. Each mutation showed a specific HRM pattern and all results were in concordance with those from direct DNA sequencing or gap-PCR methods. In cases of beta-thalassemia disease resulting from homozygosity for a mutation or compound heterozygosity for two mutations on the same amplified segment, the HRM patterns were different to those of a single mutation and were specific for each combination. HRM analysis is a simple and useful method for mutation identification in beta-thalassemia carriers and prenatal diagnosis of beta-thalassemia in northern Thailand.

Ophthalmic Evaluation in Beta-Thalassemia

OBJECTIVES

To determine the association of ocular manifestations in beta-thalassemia with the patient's age, blood transfusion requirements, average serum ferritin and dose and duration of iron chelation therapy.

METHODS

Sixty multi-transfused beta thalassemia patients of 12 to 18 y of age on chelation therapy were included in this cross-sectional analysis. Structural and functional evaluation of the retina was done using Optical coherence tomography (OCT) and Electroretinography (ERG), including flash ERG and Pattern ERG (PERG). Routine ophthalmic examination and B scan of the eye was also done. Flash ERG a-waves and b-waves were recorded, however only a-wave amplitude was evaluated. Pattern ERG n35, n95 and p50 waves were recorded and p50 wave amplitude was evaluated. The a-wave on flash and p50 on pattern waves represent retinal photoreceptor epithelium (RPE) photoreceptor response, which is mainly affected in beta-thalassemia.

RESULTS

Ocular changes were detected in 38.3% and a significant correlation was noted with increase in age (p = 0.045) but not with serum ferritin, transfusion requirements or chelation therapy. Refractive errors were found in 14 cases (23%), such as myopia with astigmatism in 13 (21.7%) and only myopia in 6 subjects (10%). OCT abnormality was noted in 1 patient (1.7%) who had thinning of central retina; right eye 132 μm and left eye 146 μm (n > 200 μm). Abnormalities were noted in a-wave amplitude on flash ERG in 20% of cases, while reduced p50 amplitude on PERG was noted in 15%.

CONCLUSIONS

A significant correlation was noted between ocular findings and increase in age, but not with serum ferritin, transfusion requirements or chelation therapy. ERG appears to be a promising tool for screening patients with beta-thalassemia and can serve as a follow-up test for evaluating retinal function.

Anti-Toxoplasma gondii antibodies in patients with beta-hemoglobinopathies: the first report in the Americas

Background

In Brazil, there have been no previous studies of Toxoplasma gondii infection in sickle cell anemia patients and carriers of severe forms of beta-thalassemia. This study evaluated T. gondii infection in patients with beta-hemoglobinopathies.

Methods

A total of 158 samples, 77 (48.7%) men and 81 (51.3%) women, were evaluated. Three groups were formed: G1 (85 patients with sickle cell disease); G2 (11 patients with homozygous beta-thalassemia; G3 (62 patients with heterozygous beta-thalassemia). ELISA was employed to identify anti-T. gondii IgM and IgG antibodies, and molecular analysis was performed to determine beta-hemoglobin mutations. Fisher’s exact test was used to compare frequencies of anti-T. gondii IgM and IgG antibodies in respect to gender and age.

Results

Anti-T. gondii IgG antibodies were found in 43.5% of individuals in G1, 18.1% in G2 and 50% in G3. All samples from G1 and G2 were seronegative for anti-T. gondii IgM antibodies, but 3.2% from G3 were seropositive. Considering anti-T. gondii IgG antibodies, no statistical significant differences were found between these groups nor in seroprevalence between genders within each group. Despite this, comparisons of the mean ages between G1, G2 and G3 were statistically significant (G2 vs. G1: p value = 0.0001; G3 vs. G1: p-value <0.0001; G3 vs. G2: p-value = 0.0001).

Conclusion

A comparison by age of patients with sickle cell anemia showed a trend of lower risk of infection among younger individuals. Therefore, this study demonstrates that T. gondii infection occurs in patients with beta-thalassemia and sickle cell anemia in Brazil as seen by the presence of anti-T. gondii IgM and IgG antibodies.

Development of a new real-time PCR screening kit for HbS and common beta-thalassemia mutations observed in Turkey

BACKGROUND/AIM

IVSI-110 (G>A), IVSI-6 (T>C), IVSII-1 (G>A), IVSII-745 (C>G), IVSI-1 (G>A), and HbS are mutations covering 76% of all the β-globin mutations in the Turkish population. In this study, our aim is to develop a reliable, fast, real-time kit for these mutations using the TaqMan probe method.

MATERIALS AND METHODS

This study included 100 individuals with beta-thalassemia or sickle cell anemia who had unknown mutations, and 21 controls with known mutations.

RESULTS

We designed a kit containing the IVSI-110 (G>A), IVSI-6 (T>C), IVSII-1 (G>A), IVSII-745 (C>G), IVSI-1 (G>A), and HbS mutations by using the real-time PCR method. One hundred patients were studied with our developed TaqMan real-time PCR kit. Of these patients, 73 (73%) were identified with the beta gene mutation. Among those 73 patients, 16 were homozygous, 54 were heterozygous, and 3 were compound heterozygous.

CONCLUSION

This reliable kit provided rapid diagnosis including 76% of the β-thalassemia mutations in Turkey.

Premature atherosclerosis in children with beta-thalassemia major: New diagnostic marker

Background

Early vascular alteration, atherosclerosis and coronary artery disease have emerged as important cardiovascular complications among beta-thalassemia major (B-TM) patients. The aims of the current study were to assess the prevalence of premature atherosclerosis among our B-TM patients, and to investigate the diagnostic value of serum Osteoprotegerin assay as an early biomarker for atherosclerosis.

Methods

This cross-sectional study was conducted at Hematology unit - Pediatric Department, Zagazig University Children Hospital- Egypt in the period from March 2014 to March 2015. A total of 115 children were enrolled in the current study; as sixty-five (65) children with beta thalassemia major aged 5–18 years, on regular blood transfusion regimen represented the patient group. While fifty (50) healthy children, with comparable age and gender, were assigned as control group. All participants were subjected to history taking, thorough clinical examination and laboratory investigations including; complete blood count, liver and kidney function tests, C- reactive protein, lipid profile, serum ferritin and serum Osteoprotegerin (OPG) assay. Also, carotid artery intima media thickness (CAIMT) was performed by duplex ultrasound for patients and controls.

Results

Our B-TM patients were transfusion-dependent for as long as 8.5 ± 3.8 years with significantly higher serum ferritin levels (2490 ± 1579 ng/dl vs 83 ± 32 ng/dl, p = 0.001), C-reactive protein (5.7 ± 5.7 vs 0.9 ± 0.9), liver enzymes and bilirubin when compared to controls. Significantly higher serum triglyceride (128 ± 20 vs 101 ± 7 mg/dL, p = 0.009) and atherogenic index of plasma (0.45 ± 0.12 vs 0.22 ± 0.04, p = 0.001) were recorded in patients than comparisons. On the contrary, total serum cholesterol (116 ± 16 vs 143 ± 5, p < 0.001), low density lipoprotein-cholesterol (LDL-C) (44 ± 9 vs 73 ± 6, p < 0.001) and high density lipoprotein cholesterol (HDL-C) (39 ± 2 vs 61 ± 5, p < 0.001), were significantly lowered in patients versus normal peers. Carotid arteries intima media thickness (CAIMT) of both side were significantly increased for patients (Rt 0.62 ± 0.2 vs. 0.29 ± 0.07 mm, p = 0.001 & Lt 0.66 ± 0.17 vs 0.29 ± 0.05 mm, p = 0.001) when compared with healthy controls, and showed positive correlation with, serum triglyceride, atherogenic index of plasma, and serum Osteoprotegerin levels. ELISA assay of serum Osteoprotegerin (OPG) revealed significantly higher levels for thalassemia patients than matched healthy controls (427 ± 102 vs. 324 ± 126 pg/ml, p = 0.02). Of particular interest is the obvious positive correlation between OPG levels and CAIMT of both sides (Rt r 0.54, p = 0.001 &Lt r 0.479, p = 0.001) and also with serum triglycerides (r 0.374, p = 0.03).

Conclusions

Subclinical atherosclerosis started prematurely in children with beta- thalassemia. Carotid artery intima media thickness represented a simple, accurate and non-invasivemodality for early detection ofatherosclerosis. It was correlated well with serum Osteoprotegerin; this finding highlighted the possible validity of OPG assay as an early predictor of atherosclerosis in thalassemia children.

The Effects of HFE Polymorphisms on Biochemical Parameters of Iron Status in Arab Beta-Thalassemia Patients

In this study, the potential effect of three HFE gene polymorphisms (C282Y, H63D and S65C) and the SLC40A1 A77D polymorphism on iron balance was investigated in 234 subjects (91 Arab beta-thalassemia major (BTM) patients, 34 beta-thalassemia trait (BTT) individuals and 109 health controls). Genotyping was done using restriction-fragment-length polymorphism and direct-sequencing. Serum-iron, total iron binding capacity, transferrin and ferritin were estimated in all BTT and BTM, and in 65 healthy controls. H63D was the only polymorphism detected in our cohort. Allele frequency was 13% in both BTM and BTT and 10% in controls with no significant difference. Serum iron, ferritin and transferrin saturation were significantly higher in normal males heterozygous for H63D as compared to homozygous wild-type males. Ferritin was significantly higher in BTT males with or without H63D polymorphism when compared to the healthy males with H/H genotype. No such difference was observed between H/H versus H/D BTT subgroups. We conclude that H63D is the only significant hemochromatosis-associated polymorphism in the Arabian Gulf region. The heterozygous state of H63D may significantly alter iron parameters in normal males. In BTT, it appears that the beta-thalassemia allele has an overriding influence on ferritin values, and this generally manifest in males.

Gene and Cell Therapy for β-Thalassemia and Sickle Cell Disease with Induced Pluripotent Stem Cells (iPSCs): The Next Frontier

In recent years, breakthroughs in human pluripotent stem cell (hPSC) research, namely cellular reprogramming and the emergence of sophisticated genetic engineering technologies, have opened new frontiers for cell and gene therapy. The prospect of using hPSCs, either autologous or histocompatible, as targets of genetic modification and their differentiated progeny as cell products for transplantation, presents a new paradigm of regenerative medicine of potential tremendous value for the treatment of blood disorders, including beta-thalassemia (BT) and sickle cell disease (SCD). Despite advances at a remarkable pace and great promise, many roadblocks remain before clinical translation can be realistically considered. Here we discuss the theoretical advantages of cell therapies utilizing hPSC derivatives, recent proof-of-principle studies and the main challenges towards realizing the potential of hPSC therapies in the clinic.

Gene Addition Strategies for β-Thalassemia and Sickle Cell Anemia

Beta-thalassemia and sickle cell anemia are two of the most common diseases related to the hemoglobin protein. In these diseases, the beta-globin gene is mutated, causing severe anemia and ineffective erythropoiesis. Patients can additionally present with a number of life-threatening co-morbidities, such as stroke or spontaneous fractures. Current treatment involves transfusion and iron chelation; allogeneic bone marrow transplant is the only curative option, but is limited by the availability of matching donors and graft-versus-host disease. As these two diseases are monogenic diseases, they make an attractive setting for gene therapy. Gene therapy aims to correct the mutated beta-globin gene or add back a functional copy of beta- or gamma-globin. Initial gene therapy work was done with oncoretroviral vectors, but has since shifted to lentiviral vectors. Currently, there are a few clinical trials underway to test the curative potential of some of these lentiviral vectors. This review will highlight the work done thus far, and present the challenges still facing gene therapy, such as genome toxicity concerns and achieving sufficient transgene expression to cure those with the most severe forms of thalassemia.