Loss-of-Function Variants in SUPT5H as Modifying Factors in Beta-Thalassemia.

It is well known that modifiers play a role in ameliorating or exacerbating disease phenotypes in patients and carriers of recessively inherited disorders such as sickle cell disease and thalassemia. Here, we give an overview of the literature concerning a recently described association in carriers of SUPT5H Loss-of-Function variants with a beta-thalassemia-like phenotype including the characteristic elevated levels of HbA2. That SUPT5H acts as modifier in beta-thalassemia carriers became evident from three reported cases in whom combined heterozygosity of SUPT5H and HBB gene variants was observed to resemble a mild beta-thalassemia intermedia phenotype. The different SUPT5H variants and hematologic parameters reported are collected and reviewed to provide insight into the possible effects on hematologic expression, as well as potential disease mechanisms in carriers and patients.

Transfusion requirements and complication rate in ß-thalassemia intermedia due to heterozygous ß-globin gene mutation and triplicated α-globin genes.

INTRODUCTION: The heterozygous condition for ß-thalassemia mutation associated with an extra functional α-globin gene can produce a Thalassemia Intermedia (TI) phenotype. This genotype is the second in frequency in the French Thalassemia Registry NaThalY that prospectively collects laboratory and clinical data. MATERIALS AND METHODS: The present report analyses transfusion needs, iron overload (ferritin, hepatic and cardiac iron concentrations), and complication rates in 45 patients included in NaThalY and presenting a heterozygous ß0 or ß+ -thalassemia mutation associated with a triplication at HBA locus. This cohort was compared to a cohort of patients with TI due to mutations in the beta-globin gene only and included in the French registry. RESULTS: Patients with an extra functional α-globin gene showed a less severe anemia, lower transfusion needs and lower complication rates than those with TI related to the ß-globin gene only. Nevertheless, some of them displayed complications such as cholelithiasis or extramedullary hematopoiesis. In addition, one third of the cohort needed transfusions and another third was under iron chelation. CONCLUSION: The genotype associating a heterozygous ß0 or ß+ -thalassemia mutation with a triplication at HBA locus should be accurately diagnosed as it could lead to symptomatic anemia and to potential iron overload and iron-related complications even in patients with no transfusion need.

An Expert Overview on Therapies in Non-Transfusion-Dependent Thalassemia: Classical to Cutting Edge in Treatment.

The thalassemia issue is a growing worldwide health concern that anticipates the number of patients suffering from the disease will soon increase significantly. Patients with ß-thalassemia intermedia (ß-TI) manifest mild to intermediate levels of anemia, which is a reason for it to be clinically located between thalassemia minor and ß-thalassemia major (ß-TM). Notably, the determination of the actual rate of ß-TI is more complicated than ß-TM. The leading cause of this illness could be partial repression of ß-globin protein production; accordingly, the rate of ß-globin gene repression is different in patients, and the gene repression intensity creates a different clinical status. This review article provides an overview of functional mechanisms, advantages, and disadvantages of the classic to latest new treatments for this group of patients, depending on the disease severity divided into the typical management strategies for patients with ß-TI such as fetal hemoglobin (Hb) induction, splenectomy, bone marrow transplantation (BMT), transfusion therapy, and herbal and chemical iron chelators. Recently, novel erythropoiesis-stimulating agents have been added. Novel strategies are subclassified into molecular and cellular interventions. Genome editing is one of the efficient molecular therapies for improving hemoglobinopathies, especially ß-TI. It encompasses high-fidelity DNA repair (HDR), base and prime editing, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 procedure, nuclease-free strategies, and epigenetic modulation. In cellular interventions, we mentioned the approach pattern to improve erythropoiesis impairments in translational models and patients with ß-TI that involve activin II receptor traps, Janus-associated kinase 2 (JAK2) inhibitors, and iron metabolism regulation.

Dominant ß-Thalassemia Phenotype Caused by Hb Dieppe (HBB: c.383A>G): Another Case Report.

Homozygous or compound heterozygous mutations of the ß-globin gene lead to ß-thalassemia (ß-thal) major (ß-TM) or ß-thal intermedia (ß-TI), whereas heterozygotes usually show microcytosis with negligible or no hemolysis. Certain missense mutations in exon 3, however, produce unstable globins causing a dominant ß-thal phenotype or hemolytic anemia in heterozygotes. Here we report a mutation in exon 3 of the ß-globin gene, which results in an unstable globin (Hb Dieppe) [ß127(H5)Gln→Arg; HBB: c.383A>G] with a dominant ß-thal phenotype in two generations of a Chinese family. Physicians should be alerted to this mechanism of ß-thal considering its relative rarity.

First Report of ß-Thalassemia Intermedia in a Patient Compound Heterozygous for -92 (C>T) and Codons 36/37 (-T) Mutations.

The -92 (C>T) (HBB: c.-142C>T) is a silent ß-thalassemia (ß-thal) mutation previously described in combination with several ß0 mutations and expressed as ß-thal intermedia (ß-TI). Heterozygous individuals are known to be completely asymptomatic showing borderline hemoglobin (Hb), mean corpuscular volume (MCV) and Hb A2 levels. Here, we report the first incidence of -92 in Eastern Europe and in Azerbaijan, and the first case in combination with codons 36/37 (-T) (HBB: c.112delT) mutation.

Pitfalls in the Diagnosis of ß-Thalassemia Intermedia.

We present case histories of three patients who had ß-thalassemia (ß-thal) trait with 'unusual severity' managed as ß-thal intermedia (ß-TI) where the basis of disease severity could not be explained with routine hematological and genetic investigations. The clinical diagnosis of 'thalassemia intermedia' was justifiable as they had a ß-thal mutation and disease severity that did not fit in with either ß-thal trait or with ß-thal major (ß-TM). As mutations of α, ß, and γ genes could not explain the unusual severity of the disease, further analysis with next-generation sequencing (NGS) for red cell diseases was carried out, which led to the diagnosis of coexisting membranopathies. This case series highlights the inherent difficulty in the diagnosis of ß-TI with certainty in some patients where the genetic basis is not clear-cut.

Association between Different Polymorphic Markers and ß-Thalassemia Intermedia in Central Iran.

ß-Thalassemia intermedia (ß-TI) is a clinical condition characterized by moderate, non transfusional anemia and hepatosplenomegaly. The main objective of this study was to determine the molecular basis of the clinical phenotype of ß-TI in Iran. To elucidate the mild phenotype of many patients with ß-TI, we screened for three prevalent ß-globin gene mutations [IVS-II-1 (G>A) HBB: c.315+1G>A, IVS-I-110 (G>A) HBB: c.93-21G>A and IVS-I-5 (G>C) [HBB: c.92+5G>C], deletions on the α-globin genes, XmnI polymorphisms and restriction fragment length polymorphism (RFLP) haplotypes on the ß-globin gene cluster in 50 ß-TI patients. Fifty-eight percent of the patients (29 cases) were associated with the mentioned mutations. We showed that the HBB: c.315+1G>A mutation is linked to haplotype [+ - + +] (57.69%). This haplotype is in linkage disequilibrium with the XmnI polymorphism (NG_000007.3: g.42677C>T) and has been associated with increased expression of Hb F in ß-TI patients. The XmnI polymorphism is defined in association with this prevalent mutation. Two patients had a single α-globin gene deletion [-α3.7 (rightward) deletion]. The main genetic factor in mild phenotype ß-TI patients is the linkage of an XmnI polymorphism (NG_000007.3: g.42677C>T) with the HBB: c.315+1G>A (80.76%), which is associated with increased production of Hb F and coinheritance of haplotype [+ - + +] with ß-TI, especially with the homozygous HBB: c.315+1G>A mutation. Molecular basis of ß-TI could be explained by the involvement of different factors that tend to develop the disease phenotype.

A De Novo Heterozygous Variant (HBB: c.379delG, p.Val127Cysfs*32) Associated with a Mild ß-Thalassemia Intermedia Phenotype in a Turkish Child.

We report a de novo heterozygous variant of the ß-globin chain that showing a mild ß-thalassemia intermedia (ß-TI) phenotype. He presented with mild anemia, splenomegaly, reticulocytosis, and poikilocytosis and tear drop cells on the blood smear; Immune mediated hemolysis, red cell membrane and enzyme defects, were excluded; hemoglobin (Hb) electrophoresis showed an elevation of Hb F. Molecular analysis of the ß-globin gene showed a heterozygous variation in exon 3 (HBB: c.379delG, p.Val127Cysfs*32) in the absence of an α-globin gene mutation or mutations that modulate Hb F expression.

Krüppel-Like Factor 1 Gene Mutations in Thalassemia Patients from North Iran: Report of a New Mutation Associated with ß-Thalassemia Intermedia.

Thalassemia is a hereditary disease with an autosomal recessive inheritance pattern resulting in reduced production of globin chains. Mutations in modifier genes can cause or affect thalassemia. Krüppel-like factor 1 (KLF1) is a modifier gene that was investigated in this study. Thirty-five Iranian ß-thalassemia (ß-thal) minor patients with hematological symptoms including Hb A2 3.0%, mean corpuscular volume (MCV) <75.0 fL, mean corpuscular hemoglobin (Hb) (MCH) <25.0 pg, and two ß-thal intermedia (ß-TI) patients in 50 subjects who carried no mutations on the HBB and HBA2 or HBA1 genes were investigated for all exons of the KLF1 gene by polymerase chain reaction (PCR) and sequencing methods. Of the 35 patients with a ß-thal minor phenotype, one patient was heterozygous for the c.544T>C mutation in exon 2 of KLF1 and HBB: c.380T>G variant, Hb Dhonburi [also known as Hb Neapolis or codon 126 (T>G)]. The c.340T>C mutation was also found in exon 2 of the KLF1 gene with an allele frequency of 16.6% in the studied ß-thal carriers. The two ß-TI patients were homozygous for a new mutation c.942delA in exon 3 of KLF1. Mutations in modifier genes can cause or affect thalassemia. Therefore, exact investigation of globin genes and modifiers such as KLF1 is necessary in areas where globin gene disorders are most prevalent to understand the reason of clinical and hematological symptoms of thalassemia and facilitate newborn screening or prenatal diagnosis (PND) programs.

Compound Heterozygosity for Silent Cap +1570 (T>C) (HBB: c*96T>C), Codon 39 (C>T) (HBB: c.118C>T) and the Presence of αααanti-3.7/αα in Greece. A Case Presentation.

The rare point mutation Cap +1570 (T>C) (HBB: c*96T>C) has been reported in families of Czech, Greek, Turkish and Italian origin. The mutation contributes to a reduction of the ß-globin chain synthesis, and in heterozygous carriers, it causes a silent phenotype, while in compound heterozygosity with severe ß-thalassemia (ß-thal) mutations, it leads to a non transfusion dependent ß-thal intermedia (ß-TI) state. We report a case of compound heterozygosity for codon 39 (C>T) (HBB: c.118C>T) and Cap +1570, in addition to the presence of αααanti-3.7/αα.

Relationship of the Interaction Between Two Quantitative Trait Loci with γ-Globin Expression in ß-Thalassemia Intermedia Patients.

Globin switching is a significant factor on blood hemoglobin (Hb) level but its molecular mechanisms have not yet been identified, however, several quantitative trait loci (QTL) and polymorphisms involved regions on chromosomes 2p, 6q, 8q and X account for variation in the γ-globin expression level. We studied the effect of interaction between a region on intron six of the TOX gene, chromosome 8q (chr8q) and XmnI locus on the γ-globin promoter, chr11p on γ-globin expression in 150 ß-thalassemia intermedia (ß-TI) patients, evaluated by statistical interaction analysis. Our results showed a significant interaction between one QTL on intron six of the TOX gene (rs9693712) and XmnI locus that effect γ-globin expression. Interchromosomal interaction mediates through transcriptional machanisms to preserve true genome architectural features, chromosomes localization and DNA bending. This interaction can be a part of the unknown molecular mechanism of globin switching and regulation of gene expression.

The association between four SNPs (rs7482144, rs4671393, rs28384513 and rs4895441) and fetal hemoglobin levels in Chinese Zhuang ß-thalassemia intermedia patients.

Four SNPs (rs7482144, rs4671393, rs28384513 and rs4895441) associated with HbF levels have been identified in different populations worldwide. To explore whether these SNPs modulate HbF expression in Chinese Zhuang population, 436 Chinese Zhuang ß-thalassemia intermedia (ß-TI) patients were divided into high HbF level group (mean HbF=25.5%, n=218) and low group (mean HbF=6.51%, n=218) for genotyping using PCR-HRM method. Results demonstrated that there was a significantly higher minor allele frequency (MAF=34.2%) of rs4895441 (G) in HMIP in high HbF level group than that in low group (MAF=19.8%) (P=0.001, OR=1.73, 95% CI: 1.24-2.57). The cumulative effects of risk genotypes of these loci for patients carrying any combination of 1, 2 or 3 risk genotype had a gradually increased risk of high HbF level phenotype compared to those without the risk genotypes (OR=1.50-9.06, P=0.0008); Gene-gene interaction of rs7842144 and rs4895441 showed the best model with the smallest prediction error (0.4259) and the greatest consistency of coefficient of variation (P=0.01). We concluded that rs4895441, G on HMIP might be a high-risk modifier variant for high HbF level expression, and HBG2, BCL11A and HMIP genes, as HbF quantitative trait loci (QTL) could have a synergistic effect on increasing the HbF level in Chinese Zhuang ß-TI patients.

Liver transplantation from a deceased donor with ß-thalassemia intermedia is not contraindicated: A case report.

The use of extended criteria donors who might have previously been deemed unsuitable is an option to increase the organ supply for transplantation. This report presents a pediatric case of a successful liver transplantation from a donor with ß-thalassemia intermedia. A patient, 6-year-old female, with a diagnosis of cryptogenic liver cirrhosis underwent deceased donor liver transplantation from a thalassemic donor. Extreme hyperferritinemia was detected shortly after transplantation. The most probable cause of hyperferritinemia was iron overload secondary to transplantation of a hemosiderotic liver. Hepatocellular injury due to acute graft rejection might have contributed to elevated ferritin levels by causing release of stored iron from the hemosiderotic liver graft. Iron chelation and phlebotomy therapies were started simultaneously in the early postoperative period to avoid iron-related organ toxicity and transplant failure. Follow-up with monthly phlebotomies after discharge yielded a favorable outcome with normal transplant functions. Thalassemia intermedia patients can be candidates of liver donors to decrease pretransplant waitlist mortality. After transplantation of a hemosiderotic liver, it is important to monitor the recipient in terms of iron overload and toxicity. Early attempts to lower iron burden including chelation therapy and/or phlebotomy should be considered to avoid organ toxicity and transplant failure.

A Clinical Update of the Hb Siirt [ß27(B9)Ala→Gly; HBB: c.83C>G] Hemoglobin Variant.

We report a clinical update of the hemoglobin (Hb) variant [ß27(B9)Ala→Gly; HBB: c.83C>G], named Hb Siirt, that was previously described as a silent variant in a 23-year-old Kurdish female. The patient was also a carrier of the codon 5 (-CT) (HBB: c.17_18delCT) frameshift mutation and of the ααα anti 3.7 triplication. Her initial moderate ß-thalassemia intermedia (ß-TI) phenotype worsened with time, causing the patient to become a transfusion-dependent subject at the age of ∼40 years. Subsequent molecular characterization of both parents revealed that the Hb Siirt variant was inherited by the mother, while the other two globin alterations (HBB: c.17_18delCT and αααanti 3.7 triplication) were genetically transmitted by the father. The latter remained a carrier of a mild ß-TI phenotype throughout his life, at least until the age of 65 years. We hypothesize that the worsened clinical conditions in the daughter were due to the additional, maternally inherited Hb Siirt variant. However, protein 3D conformational analysis did not seem to reveal substantial overall structural changes. Among the other three described variants [Hb Volga (HBB: c.83C>A), Hb Knossos (HBB: c.82 G>T), Hb Grange-Blanche (HBB: c.83C>T] that are due to nucleotide substitutions at codon 27 of the ß-globin gene; only Hb Knossos causes a ß+-thalassemia (ß+-thal) phenotype.

Homozygous Mutation on the ß-Globin Polyadenylation Signal in a Tunisian Patient with ß-Thalassemia Intermedia and Coinheritance of Gilbert's Syndrome.

We report here the clinical, hematological and molecular data in a 50-year-old patient with ß-thalassemia intermedia (ß-TI) caused by a homozygous ß+ mutation on the ß-globin gene polyadenylation (polyA) signal (AATAAA>AAAAAA). ß Haplotype analysis was accomplished by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Haplotype and framework analysis showed that this mutation is associated with the [- - - - + + +] ß haplotype and framework 1 (CCGCT) (FW1). This mutation was previously reported in the heterozygous state in association with the codon 9 (+TA) mutation in a ß-TI patient originating from Tunisia. To the best of our knowledge, this is the first report describing this mutation in the homozygous state. The case reported here, coinherited Gilbert's syndrome, which is characterized by hyperbilirubinemia. This conclusion was reached by the investigation of the promoter region [A(TA)nTAA] motif of the UGT1A1 gene, showing the (TA)6/(TA)7 genotype.

Molecular Characterization of ß-Thalassemia Intermedia in Southeast Iran.

Inheritance of mild mutations within the ß-globin gene and coinheritance of α-thalassemia (α-thal) are known as two important genetic modifiers in ß-thalassemia (ß-thal) intermedia (ß-TI). We aimed to evaluate the spectrum of ß- and α-thal mutations in ß-TI patients in Southeast Iran. Common ß- and α-globin gene mutations were detected by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and multiplex gap-PCR, respectively. There were 26 male (57.8%) and 19 female (42.2%) patients. HBB: c.92 + 5T > C [IVS-I-5 (G > C)] and HBB: c.-138C + 1G > A [IVS-II-I (G > A)] represented the prevalent alleles with respective frequencies of 60.0 and 10.0%. Other ß-globin mutations included HBB: c.-138C > T [-88 (C > T)], HBB: c.27_28insG [frameshift codons (FSC) 8/9 (+G)], HBB: c.46delT [codon 15 (-T)], HBB: c.93-22_95del (IVS-I, 25 del), and the 619 bp deletion (NG_000007.3: g.71609_72227del619). The predominant genotypic combinations were ß(0)/ß(0) (68.9%), ß(0)/ß(+ )(8.9%) and ß(+)/ß(+ )(2.2%). Coinheritance of α-thal was observed in 33.0% of the patients, with the -α(3.7) (rightward) (NG_000006.1: g.34164_37967del3804) as the most common deletion (86.0%). One patient was diagnosed with the -α(4.2) (leftward) (AF221717) and one with the - -(MED) (g.24664_41064del16401) deletions, while no patients carried the -(α)(20.5) (g.15164_37864del22701), α(-5 nt) (HBA2: c.95 + 2_95_6delTGAGG) or codon 19 (-G) (HBA2: c.56delG) mutations. The alleviating molecular mechanism was not explainable by ß(+ )or concurrent α-thal in more than half of our ß-TI patients. This encourages conducting more studies to identify other contributing factors, especially Hb F-inducing genetic modifiers.

Evaluation of the Relationship Between Hb F Levels and Nucleated Red Blood Cells with Morbidity in Non Transfusion-Dependent Thalassemia Patients.

Recognition of risk factors of morbidities in patients with ß-thalassemia intermedia (ß-TI) is an important issue that must be evaluated. Non transfusion-dependent thalassemia patients referred to the outpatient clinic of Shiraz University of Medical Science, Shiraz, South Iran were enrolled in this study between 2013 and 2014. Two peripheral blood smears were prepared for evaluating developmental stage of normoblasts. One hundred and thirty-one patients with ages ranging from 3 to 42 years (mean: 23.35 ± 7.9) were selected. Sixty-seven patients had at least one morbidity (51.1%). Osteoporosis and gallstones were the most common morbidities (33.6 and 24.4%, respectively). In the univariate model, hemoglobin (Hb), ferritin, Hb F, developmental stage of normoblasts and hydroxyurea (HU) therapy did not differ between patients with and without morbidity (p > 0.05) but mean age of patients and mean number of normoblasts were higher in patients with morbidity (p = 0.026 and p = 0.012, respectively). In the regression model, sex and splenectomy status were different between patients with and without morbidity. It seems that females and splenectomy are risk factors for morbidity in non transfusion-dependent thalassemia patients. [Sex: odds ratio (OR) = 2.21, 95% confidence interval (95% CI): 1.04-4.72, p = 0.39. Splenectomy: OR = 3.10, 95% CI: 1.12-8.59, p = 0.029.] This study shows that Hb F level and developmental stage of normoblasts does not effect the incidence of morbidities in non transfusion-dependent thalassemia patients but sex and splenectomy were effective factors in development of morbidities. Thus, splenectomy should be avoided as much as possible in patients with non transfusion-dependent thalassemia.

Genetic Variants at BCL11A and HBS1L-MYB loci Influence Hb F Levels in Chinese Zhuang ß-Thalassemia Intermedia Patients.

Increased Hb F levels can ameliorate the symptoms of ß-thalassemia (ß-thal). Due to the genetic heterogenicity of ß-thal, the relationship between genetic variants in modifier genes and Hb F level has been studied in different populations. The Chinese Zhuang has the second largest population in China and has 6.78% prevalence of ß-thal. However, the effects of these single nucleotide polymorphism (SNP) variants on the Hb F levels of ß-thal intermedia (ß-TI) patients in this population have not been reported. To explore the association between modifier loci (ß-globin gene cluster, HBS1L-MYB intergenic region and BCL11A) and Hb F levels in Chinese Zhuang ß-TI patients, 96 unrelated ß-TI patients (50 males and 46 females) with different Hb F levels were recruited and genotyped by mass spectrometry. A total of 13 SNPs were confirmed to be in a significant relationship with Hb F levels in this population. Of these, high-risk genotypes of six Hb F-associated SNPs, rs9376090, rs7776054, rs9399137, rs9389268, rs9402685 in the HBS1L-MYB intergenic region and rs189984760 in the BCL11A locus, showed association with high Hb F levels, especially for SNPs in linkage disequilibrium. One novel Hb F-associated SNP, rs189984760, was identified in our study. Our findings will be of valuable reference for correlation between modifier genes and Hb F in Chinese Zhuang populations and may lead to better understand the modifying mechanisms for ß-thal.

First description of the rs45496295 polymorphism of the C/EBPE gene in ß-thalassemia intermedia patients.

The C/EBPE gene, located in 14q11.2, encodes for a B/zip-type transcription factor. The C/EBPɛ is involved in terminal differentiation and functional maturity of granulocyte progenitor cells and in cell apoptosis during myeloid differentiation. A C/EBPE gene has recently been described as a candidate gene involved in clinical variability of ß-thalassemia (ß-thal). In this study, the C/EBPE gene was sequenced in 146 subjects divided into the severe type of ß-thal major (ß-TM) and moderate type of ß-thal intermedia (ß-TI), and a control group. The analysis identified the rs45496295 (C > T) polymorphism in the heterozygous state in 73.9% ß-TI patients, which was not the case in the ß-TM patients or in the control group. Thus, the T allele is consequently associated with the ß-TI group (p = 10-3). According to the Human Splicing Finder (version 3.0, Marseille, France), the presence of the rs45496295 polymorphism leads the creation of a new intronic exotic splicing enhancer (ESE) site. Moreover, the T allele of rs45496295 is associated with a lower transfusion regimen (p = 10-3) and a higher pretransfusion hemoglobin (Hb) rate (p = .006). The comparison of several factors concerning T allele carriers and non-carriers showed that the T allele does not act on the Hb F rate. The T allele of rs45496295, associated with moderate type of ß-thal, seems to modify the C/EBPɛ action, thereby preventing the hemolysis.