Search Results (21)

Thalassemias and hemoglobinopathies are among the most common genetic diseases worldwide and have a significant impact on public health. The decreasing cost of next-generation sequencing (NGS) has quickly enabled the development of new assays that allow for the simultaneous analysis of small nucleotide variants (SNVs) and copy number variants (CNVs) as deletions/duplications of α- and β-globin genes. Background/Objectives: This study highlighted the efficacy and rapid identification of all types of mutations in the α- and β-globin genes, including silent variants, using the Devyser Thalassemia NGS kit. Furthermore, we report the frequency of mutations identified in a total population of 2649 individuals recruited from four Italian Medical Genetics Laboratories. Methods: All samples were first hematologically characterized, and sequence analysis was conducted by using the Devyser Thalassemia NGS kit. All variants were also validated in an independent sample by a conventional molecular test. Results: A total of 1789 subjects were identified with genetic variants in the globin genes, of which 966 (53.9%) had variations in the β-gene, 480 (26.8%) had variations in the α-gene; and 307 (17.1%) had variations in both α- and β-genes. Variant analysis evidenced a heterogeneous mutation spectrum enriched with variants not usually observed in the Italian population. Conclusions: This study showed the high effectiveness and the rapid identification of all mutation types in both α- and β-globin genes, including silent variants. It should be emphasized that the NGS approach greatly shortens turnaround reporting times, overcoming the classic diagnostic flowchart which envisages multistep, subsequent, diagnostic approaches, often requiring long resolution times. Full article

Thalassemia represents a diverse group of inherited hematological disorders characterized by defective globin chain synthesis, leading to chronic anemia and associated complications. The complicated pathophysiology of beta-thalassemia involves genetic mutations or rarely deletions of the beta-globin gene on chromosome 11 whereas alpha-thalassemia involves deletions in the HBA1 and HBA2 genes or occasionally alterations to the DNA sequence in or around these genes. These mutation and deletion effects disrupt the balance of α/β-globin chain production, resulting in ineffective erythropoiesis, hemolysis, and a cascade of clinical manifestations including anemia, bone deformities, and iron overload. Advances in diagnostic techniques have enhanced our ability to detect and characterize these mutations, facilitating early and accurate diagnoses. Current management strategies encompass regular blood transfusions, the use of hydroxyurea to improve hemoglobin levels, and iron chelation therapy to prevent iron-related organ damage. Moreover, other therapeutics such as thalidomide for those not responding to hydroxyurea, Sirolimus for patients with immunodeficiencies, and use of vitamin E as an antioxidant have proven to be effective. Innovative therapies such as gene therapy and bone marrow transplantation offer promising curative potential, opening a new era in the treatment of thalassemia. This review focuses on pathophysiological mechanisms underlying thalassemia, explores the diagnostic methodologies, and highlights recent advancements in therapeutic approaches. Full article

Introduction: The NPRL3 gene is a critical component of the GATOR1 complex, which negatively regulates the mTORC1 pathway, essential for neurogenesis and brain development. Located on chromosome 16p13.3, NPRL3 is situated near the α-globin gene cluster. Haploinsufficiency of NPRL3, either by deletion or a pathogenic variant, is associated with a variable phenotype of focal epilepsy, with or without malformations of cortical development, with known decreased penetrance. Case Description: This work details the diagnostic odyssey of a neurotypical 10-year-old boy who presented at age 2 with unusual nocturnal episodes and a history of microcytic anemia, as well as a review of the existing literature on NPRL3-related epilepsy, with an emphasis on individuals with deletions who also present with α-thalassemia trait. The proband’s episodes were mistaken for gastroesophageal reflux disease for several years. He had molecular testing for his α-thalassemia trait and was noted to carry a deletion encompassing the regulatory region of the α-thalassemia gene cluster. Following the onset of overt focal motor seizures, genetic testing revealed a heterozygous loss of NPRL3, within a 106 kb microdeletion on chromosome 16p13.3, inherited from his mother. This deletion encompassed the entire NPRL3 gene, which overlaps the regulatory region of the α-globin gene cluster, giving him the dual diagnosis of NPRL3-related epilepsy and α-thalassemia trait. Brain imaging postprocessing showed left hippocampal sclerosis and mid-posterior para-hippocampal focal cortical dysplasia, leading to the consideration of epilepsy surgery. Conclusions: This case underscores the necessity of early and comprehensive genetic assessments in children with epilepsy accompanied by systemic features, even in the absence of a family history of epilepsy or a developmental delay. Recognizing phenotypic overlaps is crucial to avoid diagnostic delays. Our findings also highlight the impact of disruptions in regulatory regions in genetic disorders: any individual with full gene deletion of NPRL3 would have, at a minimum, α-thalassemia trait, due to the presence of the major regulatory element of α-globin genes overlapping the gene’s introns. Full article

The mutation HBA2:c.*94A>G (AATAAA>AATAAG; rs63751269) is a 3′-UTR (3 prime untranslated region) single-nucleotide substitution in the polyadenylation (PA) signal of HBA2 (α^PA:A→G). This pathogenic (CADD score, 14.92) variant is sporadic in the Arabian Peninsula. It results in inefficient mRNA processing, transcription termination, and possibly using an alternate cryptic downstream polyadenylation signal. As a result, the allele α^T (or α^T-Saudi) poses challenges in premarital counseling with respect to fetal risk of hemoglobin H disease. Homozygous HBA2:c.*94A>G (α^Tα/α^Tα) results in moderate-to-severe microcytosis (mean red cell volume, MCV, 55 to 65 fL), reflecting markedly impaired hemoglobin synthesis (hemoglobin H disease). Homozygous rightward −α^3.7 (a 3804-neocleotide deletion allele, NM_000517.4:c.[-2_-3delAC; −α^3.7]), on the other hand, results in mild microcytosis (MCV, 70 to 75 fL, alpha-thalassemia trait). Thus, HBA2:c.*94A>G is more damaging than −α^3.7. Consistently, the value of MCV in compound heterozygosity, HBA2:c.*94A>G and −α^3.7, is 65 to 70 fL. We report here a healthy couple who presented for premarital counseling on their hemoglobinopathy. The man has homozygous HBA2:c.*94A>G (α^Tα/α^Tα), and the woman has compound heterozygous (−α^3.7/α^Tα, also annotated as: ^−3.7α/α^Tα). As a result, the genotype of their offspring would be that of the father (α^Tα/α^Tα) or the mother (−α^3.7/α^Tα). The counseling was mainly based on the benign phenotypes of the parents. As both were asymptomatic and their anemia was clinically insignificant, they proceeded with the marriage. Full article

Background: Alpha thalassemia is one of the most common human genetic abnormalities. More than 400 different variations of the α-globin protein have been introduced, most of which are not associated with noticeable clinical manifestations. The identification of all variants of Hb in different regions helps in acquiring comprehensive knowledge concerning thalassemia disease, and it can be used in preventive programs as well as prenatal diagnosis (PND). Aims: In the present study, we describe a new α1 gene mutation that leads to a frameshift after codon 83. Methods: As a plan for a national screening program of thalassemia, routine cell blood count (CBC) and Hb capillary electrophoresis tests were applied. After taking written informed consent, genomic DNA was extracted, and, for identifying common Mediterranean α-Globin gene deletion, multiplex Gap-PCR was performed; for detecting other mutations on α- and β-Globin genes, a DNA sequencing method was used. Results: The results of CBC and capillary electrophoresis tests showed microcytosis in a female subject. The sequencing of the α-Globin gene showed that the case is heterozygote for a single-nucleotide deletion at codon 83 of the α1-Globin Gene. We named this mutation Hb Adrian (α1: c.251–T), which is a novel mutation. The mentioned mutation was also detected in the subject’s mother. Conclusions: The introduced mutation (Hb Adrian) leads to a frameshift change that produces a protein with 100 amino acids, which in comparison to a normal α-chain is shorter, and its amino acids are altered after codon 83. This hemoglobin is undetectable via the use of electrophoresis. Although no major hematological abnormalities were observed in the carriers, Hb Adrian should be considered in screening programs to help prevent Hb H disease in high-risk couples. Full article

Thalassemia is a Mendelian inherited blood disease caused by α- and β-globin gene mutations, known as one of the major health problems of Mediterranean populations. Here, we examined the distribution of α- and β-globin gene defects in the Trapani province population. A total of 2,401 individuals from Trapani province were enrolled from January 2007 to December 2021, and routine methodologies were used for detecting the α- and β-globin genic variants. Appropriate analysis was also performed. Eight mutations in the α globin gene showed the highest frequency in the sample studied; three of these genetic variants represented the 94% of the total α-thalassemia mutations observed, including the −α3.7 deletion (76%), and the tripling of the α gene (12%) and of the α2 point mutation IVS1-5nt (6%). For the β-globin gene, 12 mutations were detected, six of which constituted 83.4% of the total number of β-thalassemia defects observed, including codon β039 (38%), IVS1.6 T > C (15.6%), IVS1.110 G > A (11.8%), IVS1.1 G > A (11%), IVS2.745 C > G (4%), and IVS2.1 G > A (3%). However, the comparison of these frequencies with those detected in the population of other Sicilian provinces did not demonstrate significant differences, but it contrarily revealed a similitude. The data presented in this retrospective study help provide a picture of the prevalence of defects on the α and β-globin genes in the province of Trapani. The identification of mutations in globin genes in a population is required for carrier screening and for an accurate prenatal diagnosis. It is important and necessary to continue promoting public awareness campaigns and screening programs. Full article

α-thalassemia is characterized in about 80% of cases by deletions generated by the presence of duplications and interspersed repeated sequences in the α-globin gene cluster. In a project on the molecular basis of α-thalassemia in Southern Italy, we identified six families, showing an absence of the most common deletions, and normal α-globin gene sequences. Multiplex Ligation-dependent Probe Amplification (MLPA), qRT-PCR, and the sequencing of long-range PCR amplicon have been used for the identification and characterization of new deletions. MLPA analysis for the identification of α- and β-globin rearrangement revealed the presence of five new α-thalassemia deletions. The set-up of qRT-PCR allowed us to delimit the extent of the deletions ranging from about 10 kb to more than 250 kb, two of them being of the telomeric type. The long-range PCR generated a specific anomalous fragment in three deletions, and only several unspecific bands in the other two deletions. The sequencing of the anomalous amplicons revealed the breakpoints of two deletions: the --PA, 34 kb long, identified in two families, and the telomeric --AG, 274 kb long. The anomalous fragment containing the breakpoint of the deletion --FG was partially sequenced, and it was not possible to identify the breakpoints due to the presence of several repetitive Alu sequences. The analysis of the breakpoint regions of the --Sciacca and --Puglia, respectively, are about 10 and 165 kb long, and revealed the presence of repeats that most likely impaired the amplification of a specific fragment for the identification of the breakpoint. MLPA, in association with qRT-PCR and long-range PCR, is a good approach for the identification and molecular characterization of rare or new deletions. Breakpoint analysis confirms that Alu sequences play an important role in favoring unequal crossing-over. Southern Italy shows considerable genetic heterogeneity, as expected with its central position in the Mediterranean basin, favoring migratory flows. Full article

After the exclusion of iron deficiency and β-thalassemia, molecular research for α-thalassemia is recommended to investigate microcytic anemia. Aiming to suggest more efficiently the molecular analysis for individuals with a greater chance of having a symptomatic form of the disease, we have developed and validated a new decision tool to predict the presence of two or more deletions of α-thalassemia, increasing considerably the pre-test probability. The model was created using the variables: the percentage of HbA₂, serum ferritin and mean corpuscular volume standardized by age. The model was trained in 134 patients and validated in 160 randomly selected patients from the total sample. We used Youden’s index applied to the ROC curve methodology to establish the optimal odds ratio (OR) cut-off for the presence of two or more α-globin gene deletions. Using the OR cut-off of 0.4, the model’s negative predictive value (NPV) was 96.8%; the cut-off point accuracy was 85.4%; and the molecular analysis pre-test probability increased from 25.9% to 65.4% after the use of the proposed model. This tool aims to assist the physician in deciding when to perform molecular studies for the diagnosis of α-thalassemia. The model is useful in places with few financial health resources. Full article

One of the more common single-gene disorders worldwide is α-thalassemia, carriers of which are found at variable frequencies (>1%) across all tropical and subtropical countries. Two linked α-globin genes on each allele of chromosome 16 regulate α-globin chain production. Deletion of one or more α-globin genes is the most frequent molecular defect found in α-thalassemia, whereas non-deletional mutations also occur, leading to unstable α-globin chains. HbH is the most common clinically important α-thalassemia disease and occurs when three α-globin genes are deleted/mutated, leaving only one copy of the gene intact. HbH can be divided into deletional (--/-α) and non-deletional genotypes (--/α^Tα). Whereas clinical phenotypes of the former are usually homogenously mild to moderate, those of the latter can be diverse. As HbH disease is particularly prevalent in Southeast Asia and some parts of the Mediterranean region, where β-thalassemia is also prevalent, affected patients are sometimes left undertreated. Therefore, hematologists and general physicians need to be educated to provide optimal disease monitoring and early identification of those with more severe phenotypes. Some issues regarding transfusion and iron chelation management differ from those of β-thalassemia, and these need to be recognized. Hb Bart’s hydrops fetalis syndrome (BHFS) is the most severe form of α-thalassemia; affected patients lack production of α-globin chains. Recent advances in fetal medicine and neonatal intensive care have made it possible for BHFS to no longer constitute a universally fatal disorder. Transfusion and chelation strategies for rare survivors are distinct and require updating. Full article

This is a report of a couple with abnormal hematological indices who were investigated for α & β-thalassemia mutations. Based on CBC and capillary hemoglobin electrophoresis results, the male and female subjects were β & α-thalassemia carriers, respectively. Multiplex-Gap-PCR and Sanger sequencing techniques were used for the identification of mutations on α and β-globin genes. The DNA test showed the presence of c.315 + 1 G > A mutation on β-globin gene of male subject while the female case had – ^MED double gene deletion and c.427T > C mutation on α-globin and, interestingly, she was also a carrier for c.315 + 1 G > A mutation on β-globin gene. Cases with the coinheritance of heterozygous β⁰-thalassemia with one functional α-globin gene have normal HbA2 levels that may lead to their being misdiagnosed as β-thalassemia carriers, especially in premarital screening programs for thalassemia. Therefore, β-globin gene sequencing is recommended in cases with normal Hb electrophoresis and reduced hematological indices in premarital screening programs for thalassemia, especially in regions with a high frequency of β-globin mutations, in order to identify all the β-thalassemia carriers. Full article

Alpha thalassemia is an autosomal recessive disorder caused by large deletions and/or point mutations in the α- globin genes. Hemoglobin H (Hb H) disease is most frequently due to deletion of three of the four α globin genes associated with variable clinical severity depending on the genotype. There are few reports on Hb H disease in Indians where genotyping has been done and we have reviewed the molecular and clinical heterogeneity of these cases. An electronic search for relevant articles was conducted using two journal databases, i.e., PubMed and Science Direct using the key words “Hb H Disease”, “Hemoglobin H”, “α-thalassemia”, “mutations”, “molecular heterogeneity”, “case reports” and “India”. This review was performed based on preferred reporting items for the systematic review and meta-analysis protocols (PRISMA-P) guidelines. The molecular spectrum of Hb H disease in Indians includes the most common [-α^3.7, -α^4.2, --^SA, Poly A (AATAAA→AATA--), Hb Sallanches], rare [--^SEA, --^MED, IVS 1nt 1 (G→A), Hb Koya Dora, Hb Sun Prairie], very rare [Hb Iberia, Hb Seal Rock, Hb Zürich-Albisrieden] and novel [Codon 76 (+T) and --^Kol] α-globin gene mutations inherited largely as compound heterozygotes with considerable clinical variability. The molecular diagnosis of Hb H disease is important for genetic counseling and management. Full article

The interactions of δ-globin variants with α- and β-thalassemia or other hemoglobinopathies cause complex thalassemic syndromes and potential diagnostic problems. Understanding the molecular basis and phenotypic expression is crucial. Four unrelated Thai subjects with second hemoglobin (Hb) A₂ fractions were studied. A standard automated cell counter was used to acquire initial hematological data. Hb analysis was carried out by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) assays. Globin gene mutations and haplotype were identified by appropriate DNA analysis. An allele-specific polymerase chain reaction method was developed to provide a simple molecular diagnostic test. Hb analysis revealed a Hb A₂ variant in all cases. DNA analysis of the δ-globin gene identified the Hb A₂-Melbourne [δ43(CD2)Glu > Lys] variant in combination with Hb E in three cases. Analysis of the remaining case identified a novel δ-Hb variant, namely Hb A₂-Mae Phrik [δ52(D3)GAT > GGT; Asp > Gly], found in association with Hb E and α⁺-thalassemia, indicative of the as yet undescribed combination of triple heterozygosity of globin gene defects. An allele-specific PCR-based assay was successfully developed to identify this variant. The β-haplotype of the Hb A₂ Mae-Phrik allele was strongly associated with haplotype [+ − − − − ± +]. This study advanced our understanding of the phenotypic expression of known and novel δ-Hb variants coinherited with other globin gene defects, routinely causing problems with diagnosis. Therefore, knowledge and recognition of this Hb variant and molecular assessments are crucial to improving diagnosis. Full article

The Corfu δ⁰β⁺ thalassemic allele is a unique thalassemic allele consisting of the simultaneous presence in cis of a deletion of the δ-globin (Hemoglobin Subunit Delta, HBD) and a single nucleotide variant in the β-globin gene (Hemoglobin Subunit Beta, HBB). The allele has, so far, been described in individuals of Greek origin. The objectives of the study are to ascertain the prevalence of the Corfu δ⁰β⁺ allele in comparison to other β-thalassemia variants encountered in Greece using our in-house data repository of 2558 β-thalassemia heterozygotes, and to evaluate the hematological phenotype of Corfu δ⁰β⁺ heterozygotes in comparison to heterozygotes with the most common β⁺- and deletion α⁰- thalassemia variants in Greece. The results of the study showed a relative incidence of heterozygotes with Corfu δ⁰β⁺ at 1.56% of all β-thalassemic alleles, and a distinct hematological phenotype of the heterozygotes characterized by microcytic, hypochromic anemia with normal levels of HbA₂ (Hemoglobin A2) and elevated HbF (Hemoglobin F) levels. The application of a specific methodology for the identification of the Corfu δ⁰β⁺ allele is important for precise prenatal and antenatal diagnosis programs in Greece. Full article

An insertion or deletion of a nucleotide (nt) in the penultimate or the last exon can result in a frameshift and premature termination codon (PTC), giving rise to an unstable protein variant, showing a dominant phenotype. We described two α-globin mutants created by the deletion of a nucleotide in the penultimate or the last exon of the α1-globin gene: the Hb Campania or α1 cod95 (−C), causing a frameshift resulting in a PTC at codon 102, and the Hb Sciacca or α1 cod109 (−C), causing a frameshift and formation of a PTC at codon 133. The carriers showed α-thalassemia alterations (mild microcytosis with normal Hb A2) and lacked hemoglobin variants. The 3D model indicated the α-chain variants’ instability, due to the severe structural alterations with impairment of the chaperone alpha-hemoglobin stabilizing protein (AHSP) interaction. The qualitative and semiquantitative analyses of the α1mRNA from the reticulocytes of carriers highlighted a reduction in the variant cDNAs that constituted 34% (Hb Campania) and 15% (Hb Sciacca) of the total α1-globin cDNA, respectively. We developed a workflow for the in silico analysis of mechanisms triggering no-go decay, and its results suggested that the reduction in the variant mRNA was likely due to no-go decay caused by the presence of a rare triplet, and, in the case of Hb Sciacca, also by the mRNA’s secondary structure variation. It would be interesting to correlate the phenotype with the quantity of other frameshift mRNA variants, but very few data concerning α- and β-globin variants are available. Full article

Most α-thalassemia cases are caused by deletions of the structural α-globin genes. The degree of microcytosis and hypochromia has been correlated with the number of affected α-globin genes, suggesting a promising role of hematologic parameters as predictive diagnostic tools. However, cut-off points for these parameters to discriminate between the different subtypes of α-thalassemia are yet to be clearly defined. Six hematologic parameters (RBC, Hb, MCV, MCH, MCHC and RDW) were evaluated in 129 cases of deletional α-thalassemia (56 heterozygous α⁺ thalassemia, 36 homozygous α⁺ thalassemia, 29 heterozygous α⁰ thalassemia and 8 cases of Hb H disease). A good correlation between the number of deleted alpha genes and MCV (r = −0.672, p < 0.001), MCH (r = −0.788, p < 0.001) and RDW (r = 0.633, p < 0.001) was observed. The presence of an α⁰ allele should be discarded in individuals with microcytosis without iron deficiency and normal values of Hb A₂ and Hb F with MCH < 23.40 pg. Furthermore, MCH < 21.90 pg and/or MCV < 70.80 fL are strongly suggestive of the presence of one α⁰ allele. Finally, an accurate presumptive diagnosis of Hb H disease can be made if both RDW ≥ 20% and MCH < 19 pg are seen. Full article