ABO serology in a case of persistent weak A in a recipient following a group O-matched unrelated bone marrow transplant.

CONCLUSIONS: HLA-matched hematopoietic stem cell transplantation (HSCT) from red blood cell (RBC)-incompatible donors is not uncommon. The engraftment process following ABO-incompatible allogeneic HSCT results in the transition from patient blood group to donor blood group in the recipient. In contrast, most non-hematopoietic tissues retain expression of the patient's original blood group for life, and these antigens may adsorb from the plasma onto the donor-derived RBCs. Correct serologic interpretation of the ABO blood group during this engraftment process can be difficult. We present the serologic findings of a 15-year-old girl of Maori descent, who was diagnosed with acute myeloid leukemia and transplanted with an HLA-matched unrelated group O, D+ bone marrow. Despite engraftment, her RBCs showed persistence of weak A. This case report showcases the importance of awareness and correct serologic interpretation of weak persistence of recipient ABH substance on the patient's RBCs for clinical decision-making, blood component support, and patient wellbeing.

RNF187 is Downregulated Following NF-κB Inhibition in Late Erythroblasts.

Beta (ß)-thalassaemic erythroblasts grown in vitro have reduced nuclear factor kappa B (NF-κB) pathway gene expression. By inhibiting this pathway in erythroblasts from normal individuals, important downstream genes affected by this inhibition can be identified. Bay 11-7082 is a potent inhibitor of the NF-κB pathway, it acts irreversibly, inhibiting NF-κB activation by blocking tumor necrosis factor alpha (TNF-α)-induced phosphorylation of the inhibitory IκB subunit thereby preventing NF-κB activation. In this study, hematopoietic stem cells were isolated from the peripheral blood of 6 healthy individuals and were then cultured for 14 days in conditions which promote erythroid differentiation. Following erythroid lineage enrichment, these cells were stimulated with TNFα or inhibited with Bay 11-7082. Subsequent RNA isolation and gene expression analyses were performed using pooled cDNA with custom PCR arrays. Genes of interest were examined individually on non-pooled samples. Our data identified RNF187, a RING finger domain gene as being downregulated in response to NF-κB inhibition.

The Effect of Nonsense Mediated Decay on Transcriptional Activity Within the Novel ß-Thalassemia Mutation HBB: c.129delT.

Premature termination codons (PTCs) are caused by mutations in the coding sequences of functional genes resulting in an incorrect assignment of a stop codon. Abnormal and truncated proteins are prevented from being translated due to the rapid degradation of mRNA carrying these mutations by an RNA surveillance mechanism referred to as nonsense mediated decay (NMD). Recently, a novel mutation in a patient from Thailand with the clinical diagnosis of Hb E (HBB: c.79G > A)/ß(0)-thalassemia (Hb E/ß(0)-thal) and whose molecular analysis demonstrated a novel mutation in the ß-globin gene, HBB: c.129delT, was reported. The result of this deletion is a frameshift (FSC) resulting in a PTC at codon 60. We have analyzed the impact of this mutation on transcription and translation of the affected ß-globin gene using an in vitro model. The quantitative real-time polymerase chain reaction (qReTi-PCR) analysis revealed that this nucleotide mutation resulted in marked mRNA degradation, which we attributed to the NMD mechanism and as such, the expected deleterious truncated HBB was not generated. This result highlights a valuable application of our in vitro gene expression model that can be used to predict possible molecular pathology for any given nucleotide mutations.

Experimental Characterization of Hb Flurlingen (HBA2: c.177 C > G, p.His > Gln) and Hb Boghé (HBA2: c.177 C > A, p.His > Gln) Reveals Contradictory HBA2 Expression and Translation Patterns Despite Identical Amino Acid Substitutions.

In this study, we describe the clinical features and provide experimental analyses of Hb Flurlingen (HBA2: c.177 C > G, p.His > Gln) that contrasted with Hb Boghé (HBA2: c.177 C > A, p.His > Gln). Despite the identical amino acid substitution in both variants, Hb Flurlingen shows the phenotype of α-thalassemia (α-thal), whereas Hb Boghé has no impact on α2-globin (HBA2) production. For in vitro transcription analysis, HBA2 expression constructs carrying the HBA2-WT (wild type), Hb Flurlingen and Hb Boghé sequences were generated and expressed in human bladder carcinoma 5637 cells for downstream analyses by quantitative real time-polymerase chain reaction (qReTi-PCR) and immunofluorochemistry (IFC). In silico analysis of secondary folding structures of the HBA2-WT, Hb Flurlingen and Hb Boghé mRNA sequences was performed using Mfold software. The gene transcription and translation analyses revealed that cells transfected with the Hb Flurlingen construct had significantly lower HBA2 transcription (-55.4%, p ≤ 0.01) and reduced protein synthesis when compared to the wild type group. In contrast, cells transfected with the Hb Boghé construct showed no significant changes in HBA2 transcription or translation activities when compared to the wild type group. The in silico prediction of possible effects of these mutations on the folding structures of the HBA2 transcripts showed a change of secondary folding pattern in the Hb Flurlingen transcript when compared to those of HBA2-WT and Hb Boghé. Our experimental findings support the clinical presentation of an α-thalassemic phenotype for Hb Flurlingen in contrast with Hb Boghé, despite identical amino acid substitutions. The results confirm the importance of experimental analysis in establishing the impact of novel base substitutions.

BRAF mutation detection in hairy cell leukaemia from archival haematolymphoid specimens.

Hairy cell leukaemia (HCL) is a rare, indolent chronic B-cell leukaemia accounting for approximately 2% of all adult leukaemias. The recent association of the BRAF p.Val600Glu (V600E) mutation in HCL makes it a valuable molecular diagnostic marker. We compared the ability of Sanger sequencing, fluorescent single-strand conformational polymorphism (F-SSCP) and high resolution melting (HRM) analysis to detect BRAF mutations in 20 cases of HCL consisting of four archival Romanowsky stained air-dried peripheral blood and bone marrow aspirate smears, 12 mercury fixed decalcified bone marrow trephine biopsies, three formalin fixed, paraffin embedded (FFPE) splenectomy samples and one fresh peripheral blood sample. DNA was amplified and BRAF mutation status determined by the three methods above. V600E mutation was identified in 94%, 89% and 72% of HCL cases by F-SSCP, HRM and Sanger sequencing, respectively. In one case, in addition to the p.Val600Glu mutation, a p.Lys601Thr (K601T) mutation was identified. DNA from archival slide scrapings, mercury-fixed and FFPE tissue can be used to identify BRAF mutations with high sensitivity, especially using HRM/F-SSCP. The V600E mutation can be used as a supplementary molecular marker to aid in the diagnosis of HCL and the presence of the mutation may provide a target for therapy.

Differential gene expression analysis in early and late erythroid progenitor cells in ß-thalassaemia.

ß- thalassaemia is a disorder of globin gene synthesis resulting in reduced or absent production of the ß-globin chain in red blood cells. In this study, haematopoietic stem cells were isolated from the peripheral blood of six transfusion dependent ß-thalassaemia patients and six healthy controls. Following 7 and 14 d in culture, early- and late- erythroblasts were isolated and purified. No morphological difference in maturation was observed following 7 d in culture, while a delayed maturation was observed in the patient group after 14 d. Following RNA isolation and linear amplification, gene expression analyses were performed using microarray technology. The generated data were analysed by two methods: the BRB-ArrayTools platform and the Bioconductor platform using bead level data. Following 7 d culture, there was no difference in gene expression between the control and patient groups. Following 14 d culture, 384 differentially expressed genes were identified by either analysis. A subset of 90 genes was selected and the results were confirmed by Quantitative-Real-Time-polymerase chain reaction. Pathways shown to be significantly altered in the patient group include apoptosis, MAPKinase and the nuclear factor-κB pathway.

Molecular characterization of Hb Hamilton Hill (HBA2: c.388delC), a novel HBA2 variant generating a premature termination codon and truncated HBA2 chain.

In recent years, the identification of α-thalassemias caused by nondeletional mutations has increased significantly due to the advancement of sensitive molecular genetics tools. We report clinical and experimental data for a novel frameshift mutation caused by a single base deletion at position 388 in exon 3 of the α2-globin gene (HBA2: c.388delC; Hb Hamilton Hill), resulting in the phenotype of α-thalassemia (α-thal). Hb Hamilton Hill was identified in an adult female of unknown ethnicity investigated for unexplained microcytosis. Direct DNA sequencing of the HBA2 gene revealed a heterozygous mutation, HBA2: c.388delC, and the molecular effect of this mutation was assessed experimentally using our previously described in vitro model. The experimental analysis involved transfection of a human bladder carcinoma (5637) cell line with expression vectors carrying either HBA2-wild type (HBA2-WT) or HBA2: c.388delC followed by total RNA purification and cDNA synthesis. Both wild type and mutant gene expression was studied and compared at the transcriptional and translational levels using quantitative real time polymerase chain reaction (qReTi-PCR) and immunofluorochemistry (IFC), respectively. Our experimental data showed a significant reduction by 25.0% (p = 0.04) in the transcriptional activity generated from HBA2: c.388delC compared to HBA2-WT. As a result of this base deletion, a frameshift in the open reading frame generates a premature termination codon (PTC) at codon 132 of exon 3 resulting in the formation of a truncated α-globin chain. The truncated α-globin chain, observed by the IFC technique, is most likely unstable and undergoes a rapid turnover resulting in the thalassemic phenotype.

Validation of the immunochromatographic strip for α-thalassemia screening: a multicenter study.

α(0)-Thalassemia occurs from a deletion of 2 linked α-globin genes and interaction of these defective genes leads to hemoglobin (Hb) Bart's hydrops fetalis, the most severe and lethal thalassemia syndrome. Identification of α(0)-thalassemia carriers is thus essential for the prevention and control program. An immunochromatographic (IC) strip test was developed for rapid screening of α(0)-thalassemia by testing for Hb Bart's in the blood samples using a specific monoclonal antibody against Hb Bart's. To evaluate its sensitivity and specificity, the IC strip test was assessed in a cohort with various thalassemia genotypes from 4 different laboratories in Thailand and Australia. The result showed 97% sensitivity in α-thalassemia carriers with 2 α-globin genes deletion and Hb H disease. This is, in particular, the useful rapid screening test for regions where ß-thalassemia and homozygous Hb E are also common. Similar hematologic and Hb data make it impossible to address the concomitant inheritance of α(0)-thalassemia in these samples without polymerase chain reaction (PCR)-based techniques, leading to misdiagnosis of the risk of having Hb Bart's hydrops fetalis. However, α-globin genotyping should be carried out in samples with positive IC strip as positive reactivity was also observed in homozygous α(+)-thalassemia carriers who have 2 trans α-globin gene deletions. These results indicate that in combination with red blood cell indices, the IC strip test could rule out mass populations for further α(0)-thalassemia detection by PCR-based analysis. The Alpha Thal IC strip also has the potential to replace testing for Hb H inclusion bodies, as it appears to be more sensitive, specific, and less labor intensive.

Molecular and cellular analysis of a novel HBA2 mutation (HBA2: c.94A > G) shows activation of a cryptic splice site and generation of a premature termination codon.

In this study, we describe the clinical features and provide experimental analyses of a novel point mutation affecting the penultimate nucleotide of the first exon of the HBA2 (HBA2: c.94A > G) gene identified in a 26-year-old female who also carries a heterozygous Hb E (HBB: c.79G > A) variant. The aim of the study was to investigate the impact of this point mutation on the transcriptional activity of the HBA2 gene using a combination of an initial in silico prediction followed by in vitro mutagenesis and transcriptional activity assessment. The analyses revealed that the HBA2: c.94A > G point mutation causes the activation of a cryptic splice site located 49 bp upstream of the exon1-intron1 boundary in both HBA2 long and short isoforms, thus generating a frameshift and a premature termination codon between codons 48 and 49 in the second exon. A rapid degradation of the aberrantly spliced transcripts by the nonsense mediated decay (NMD) surveillance system is highly indicative of an α-thalassemia (α-thal) phenotype. However, the abnormal mRNA may not be entirely degraded since the proband presents a slight splenomegaly that could be the sign of extra vascular hemolysis.

Molecular and cellular analysis of three novel alpha2-globin gene promoter mutations [HBA2: c.-59C>T], [HBA2: c.-81C>A] and [HBA2: c.-91G>A] reveal varying patterns of transcriptional and translational activities.

While point mutations affecting the promoter region of ß-globin gene are widely described, there are no well characterised reports of any point mutations currently found in the promoter of the α2-globin (HBA2) gene. We present clinical and experimental data for three novel HBA2 gene core and proximal promoter mutations. Using an in vitro system designed to assess the impact of point mutations, the three novel [HBA2:c.-59C>T], [HBA2:c.-81C>A] and [HBA2:c.-91G>A] promoter mutations identified in three unrelated patients were analysed for HBA2 gene transcriptional and translational activities. Following the generation and transfection of expression vectors carrying each mutation, the HBA2 transcription activity of the promoters from each mutant was analysed with quantitative real time-PCR (qReTi-PCR) technique. Immunofluorochemistry (IFC) was used to analyse HBA2 protein synthesis. The analyses showed that [HBA2:c.-59C>T] and [HBA2:c.-91G>A] mutant constructs caused significant reduction in the HBA2 transcription levels by 53.7% (p = 0.0008) and 36.2% (p = 0.004), respectively, resulting in markedly lower HBA2 protein labelling when compared to the wild type as shown with subsequent IFC analysis. Conversely, the [HBA2:c.-81C>A] construct showed no significant changes in either transcription (p = 0.089) or in protein labelling when compared to the wild type. The equal pAmp transcription levels found in each group confirmed that the observed labelling differences were not due to varying transfection efficiencies. This study emphasises the importance of in vitro studies to establish the impact of base substitutions on the level of gene expression, and the value of these studies in clinicopathological correlation so that appropriate advice can be given in genetic counselling.

Alpha thalassaemia due to non-deletional mutations on the -3.7 alpha globin fusion gene: laboratory diagnosis and clinical importance.

AIMS: Alpha (α) thalassaemia may be caused by large deletions of the α globin gene(s), or rarely, non-deletional mutations. Both types of mutations may co-exist, and if located on the same allele (α), produce a reproductive risk of hydrops fetalis. We illustrate how clinical-laboratory correlation and accurate α gene sequencing are essential in identifying such patients. METHOD: Nine asymptomatic patients with -α thalassaemia trait were noted to have significant microcytosis that was insufficiently explained by a single α deletion. Hence α1 and α2 globin gene sequencing were performed, which detected a non-deletional mutation in all patients. A new set of α1 specific primers were designed for separate sequencing of the α1 gene and the -α fusion gene, respectively, so that the non-deletional mutation could be localised to the correct allele. RESULTS: In six of nine patients tested, the non-deletional mutation was on the α1 globin gene. In three patients the mutation was located on the -α fusion gene. The latter group functionally has an α allele (αα/-) with a reproductive risk for Hb Barts hydrops fetalis. CONCLUSION: Non-deletional mutations can occur on the α globin gene or a fusion gene such as the -α allele. Identification and accurate localisation of these mutations is important as this can have significant reproductive implications.

Differential expression of the Bcl-2 and Bax isoforms in CD19 positive B-lymphocytes isolated from patients diagnosed with chronic lymphocytic leukaemia.

AIM: To examine the relative gene expression levels of the anti-apoptotic Bcl-2α and ß isoforms and the pro-apoptotic Baxα and ß isoforms in patients with chronic lymphocytic leukaemia (CLL) and healthy controls (HC). METHODS: Peripheral blood was obtained from 36 patients diagnosed with CLL and 10 HC. CD19 B-lymphocytes were isolated using an antibody coupled magnetic bead isolation system; from these cells the total RNA was isolated and purified. The relative levels of gene expression were examined by quantitative real-time polymerase chain reaction (qReTi-PCR) using primers specific for each isoform. RESULTS: Bcl-2α and Baxα are expressed at higher levels than their ß-isoforms in CLL and HC. Bcl-2α, Bcl-2ß and Baxß expression is increased in CLL while Bax-α is expressed at similar levels to HC. The Bcl-2α/Bcl-2ß ratio is similar in CLL and HC. The Bcl-2α/Baxα ratio is increased in CLL when compared with HC. CONCLUSION: Bcl-2α and Baxα appear to be the dominant anti- and pro-apoptotic isoforms in CLL. The Bcl-2α/Baxα ratio is increased in CLL while the Bcl-2α/Bcl-2ß ratio is similar to HC.

α-thalassemia trait caused by frameshift mutations in exon 2 of the α2-globin gene: HBA2:c.131delT and HBA2:c.143delA.

We describe two frameshift mutations associated with an α-thalassemia (α-thal) phenotype, identified in three unrelated individuals investigated for persistent microcytosis. The first mutation, HBA2:c.131delT, is located in codon 43, and the second, HBA2:c.143delA, is located in codon 47. Both are due to single base pair deletions that cause a frameshift and a premature termination codon (PTC) at positions 48/49. The presence of a PTC at this position has been documented to result in nonsense mediated mRNA decay that would account for the thalassemic phenotype.

Identification and characterization of two novel and differentially expressed isoforms of human α2- and α1-globin genes.

In most references, the transcription initiation site for the α2- and α1-globin genes has been described to lie 37 bp upstream of the translation initiation codon, however, a review of data repositories such as GenBank and Ensembl showed a report of the α2-globin transcription initiation site occurring at position -66 relative to the initiation codon. To confirm the occurrence of these isoforms for both the α2- and α1-globin genes and to document their expression levels, we initiated our current investigation. Total RNA from the peripheral blood of 15 healthy volunteers was analyzed using both semi-quantitative-polymerase chain reaction (PCR) and real-time (ReTi-PCR) protocols developed in our laboratory, with primers designed to enable distinction between the α2- and α1-globin transcripts.We observed two distinct PCR products for each of the globin genes. Subsequent DNA sequencing of 11 individual PCR products revealed that the α2- and α1-globin transcripts are present in both a long and a short isoform, initiating at positions -66 and -37, respectively. The shorter (-37) isoform is expressed approximately 10,000-100,000 times more strongly than the longer isoform, demonstrating differential expression within the healthy population. This study, for the first time, confirms the presence of two isoforms for both the α2- and α1-globin genes with varying transcription levels in healthy individuals. The short isoform is expressed at significantly higher levels than the longer isoform for both α2 and α1 genes. Therefore, based on our observations, we propose that despite the contribution of the long isoforms to the total α-globin RNA pool, the short isoforms are the main physiological transcripts.

A molecular tool to assess the pathological relevance of alpha-globin DNA variants.

AIM: While the phenotype for heterozygous beta-thalassaemia is straightforward, it is more difficult to confirm a causative relationship for mutations in the alpha-globin genes. The aim of this study was to generate an in vitro system to evaluate the pathological relevance of α-globin mutations. METHODS: The novel variant HBA1:c.301-3C>G was used as a model. In silico analysis predicted an aberrant acceptor splice site in the mutant sequence. Subsequent in vitro studies included generation of and transfection of an expression vector carrying the HBA1:c.301-3C>G mutation, RNA purification, reverse-transcription polymerase chain reaction (RT-PCR) and cDNA sequencing. Immunofluorochemistry (IFC) with antibodies specific to the N- and or C- terminal of the α-globin protein was used in protein detection. RESULTS: In vitro molecular characterisation of this point mutation confirmed the preferential utilisation of a cryptic splice site at intron 2 of the pre-mRNA, resulting in a shift in the reading frame causing a premature termination codon (PTC) at codons 101/102 and generation of a truncated protein. CONCLUSION: We have described here a molecular tool to study mutations that affect α-globin pre-mRNA splicing and translation. We confirm in silico predictions of the consequences of the HBA1:c.301-3C>G mutation, proving aberrant RNA splicing and the production of a truncated α-globin protein.

Molecular and cellular characterization of a new α-thalassemia mutation (HBA2:c.94A>C) generating an alternative splice site and a premature stop codon.

The identification of α-thalassemia (α-thal) due to point mutations has been increasing significantly with the advancement of molecular diagnostic tools. We describe here the molecular and cellular characteristics of the thalassemia mutation HBA2:c.94A>C, a novel point mutation affecting the α2-globin gene, causing a mild α-thal phenotype in a male patient of undisclosed ethnicity, investigated for unexplained microcytosis. The detected mutation is located at the penultimate nucleotide (nt) of the first exon which we postulated might affect pre mRNA splicing. While an in silico analysis did not predict any aberrant splice variants, experimental analysis using our in vitro model for gene expression studies showed utilization of a cryptic splice site at codon 15 that resulted in an aberrant splice variant. As a result, a frameshift in the reading frame of the mature mRNA was produced, leading to the formation of a premature termination codon (PTC) between codons 48 and 49 in exon 2. This in turn leads to nonsense mediated mRNA decay (NMD) and the phenotype of α-thal.

In vitro characterization of the α-thalassemia point mutation HBA2:c.95+1G>A [IVS-I-1(G>A) (α2)].

The α-thalassemias are a group of disorders occurring as a result of decreased synthesis of α-globin chains, most commonly due to deletions of α-globin genes. Detection of α-thalassemia (α-thal) caused by point mutations has increased during the past few years and more than 70 different point mutations have been reported for the α1- and α2-globin genes. The mutation at the splice donor site of the first intervening sequence [IVS-I-1 (G>A)] of the α2-globin gene, HBA2:c.95+1G>A, is thought to cause a thalassemic phenotype by interfering with and preventing the normal splicing of pre-mRNA. We developed an in vitro expression system to study α-globin gene point mutations at the molecular and cellular levels. The expression vector carrying the HBA2:c.95+1G>A mutation (α2G(IVS-I-1G>A)) was created using site-directed mutagenesis of a wild type (WT) construct of the α2-globin gene (α2G(2034WT)). Gene expression experiments in human bladder carcinoma 5637 cells were carried out using sequence verified WT and mutated clones. Complementary DNA synthesis and polymerase chain reaction (PCR) analysis showed normal α2-globin transcripts from cells transfected with the WT vector, but aberrant transcripts from cells transfected with the mutated vector carrying the splice donor site mutation. In the presence of the G>A mutation, normal splicing does not occur, and a cryptic splice site 49 bp upstream of the normal site is used. The translation of this product produces a premature termination codon, thus resulting in a thalassemic phenotype.

Hb Lynwood [α107(G14) (-T) (α2) HBA2:c.323delT)] in conjunction with the α(3.7) deletion produces a moderately severe α-thalassemia phenotype.

We describe a novel frameshift mutation associated with an α-thalassemia (α-thal) phenotype in a patient of Sudanese origin investigated for persistent microcytosis. In addition to the α(3.7) deletion, a novel mutation on the α2 gene was detected: HBA2:c.323delT. This mutation causes a frameshift at codon 107 of the α2 gene. The result is a disturbed amino acid sequence for the following 24 amino acids, and a premature termination codon at position 132.