Rapid analysis of -alpha 3.7 thalassaemia and alpha alpha alpha anti 3.7 triplication by enzymatic amplification analysis

Ancestry of the major long-range regulatory site of the α-globin genes in the Portuguese population with the common 3.7 kb α-thalassemia deletion

BACKGROUND

The α-Major Regulatory Element (α-MRE), also known as HS-40, is located upstream of the α-globin gene cluster and has a crucial role in the long-range regulation of the α-globin gene expression. This enhancer is polymorphic and several haplotypes were identified in different populations, with haplotype D almost exclusively found in African populations. The purpose of this research was to identify the HS-40 haplotype associated with the 3.7 kb α-thalassemia deletion (-α3.7del) in the Portuguese population, and determine its ancestry and influence on patients' hematological phenotype.

METHODS AND RESULTS

We selected 111 Portuguese individuals previously analyzed by Gap-PCR to detect the presence of the -α3.7del: 50 without the -α3.7del, 34 heterozygous and 27 homozygous for the -α3.7del. The HS-40 region was amplified by PCR followed by Sanger sequencing. Four HS-40 haplotypes were found (A to D). The distribution of HS-40 haplotypes and genotypes are significantly different between individuals with and without the -α3.7del, being haplotype D and genotype AD the most prevalent in patients with this deletion in homozygosity. Furthermore, multiple correspondence analysis revealed that individuals without the -α3.7del are grouped with other European populations, while samples with the -α3.7del are separated from these and found more closely related to the African population.

CONCLUSION

This study revealed for the first time an association of the HS-40 haplotype D with the -α3.7del in the Portuguese population, and its likely African ancestry. These results may have clinical importance as in vitro analysis of haplotype D showed a decrease in its enhancer activity on α-globin gene.

BMP6 and VDR gene polymorphisms are associated with osteonecrosis in a sickle cell anaemia cohort

The occurrence and severity of osteonecrosis in sickle cell anaemia (SCA) vary due to risk factors, including genetic modifiers. Bone morphogenetic proteins (BMPs), particularly BMP6, and the vitamin D receptor (VDR) play key roles in cartilage and bone metabolism, making them potential contributors to orthopaedic outcomes in SCA. Here, we evaluated the association of polymorphisms in BMP6 (rs3812163, rs270393 and rs449853) and VDR (FokI rs2228570 and Cdx2 rs11568820) genes with osteonecrosis risk in a Brazilian SCA cohort. A total of 177 unrelated SCA patients were selected. The AA genotype of BMP6 rs3812163 was independently associated with a lower osteonecrosis risk (p = 0.015; odds ratio (OR): 0.38; 95% confidence interval (CI): 0.18-0.83) and with the long-term cumulative incidence of osteonecrosis (p = 0.029; hazard ratio: 0.56, 95% CI: 0.34-0.94). The VDR rs2228570 TT genotype was independently associated with a lower osteonecrosis risk (p = 0.039; OR: 0.14; 95% CI: 0.02-0.90). In summary, our results provide evidence that BMP6 rs3812163 and the VDR rs2228570 might be implicated in osteonecrosis pathophysiology in SCA and might help identify individuals at high risk.

Human NCR3 gene variants rs2736191 and rs11575837 alter longitudinal risk for development of pediatric malaria episodes and severe malarial anemia

BACKGROUND

Plasmodium falciparum malaria is a leading cause of pediatric morbidity and mortality in holoendemic transmission areas. Severe malarial anemia [SMA, hemoglobin (Hb) < 5.0 g/dL in children] is the most common clinical manifestation of severe malaria in such regions. Although innate immune response genes are known to influence the development of SMA, the role of natural killer (NK) cells in malaria pathogenesis remains largely undefined. As such, we examined the impact of genetic variation in the gene encoding a primary NK cell receptor, natural cytotoxicity-triggering receptor 3 (NCR3), on the occurrence of malaria and SMA episodes over time.

METHODS

Susceptibility to malaria, SMA, and all-cause mortality was determined in carriers of NCR3 genetic variants (i.e., rs2736191:C > G and rs11575837:C > T) and their haplotypes. The prospective observational study was conducted over a 36 mos. follow-up period in a cohort of children (n = 1,515, aged 1.9-40 mos.) residing in a holoendemic P. falciparum transmission region, Siaya, Kenya.

RESULTS

Poisson regression modeling, controlling for anemia-promoting covariates, revealed a significantly increased risk of malaria in carriers of the homozygous mutant allele genotype (TT) for rs11575837 after multiple test correction [Incidence rate ratio (IRR) = 1.540, 95% CI = 1.114-2.129, P = 0.009]. Increased risk of SMA was observed for rs2736191 in children who inherited the CG genotype (IRR = 1.269, 95% CI = 1.009-1.597, P = 0.041) and in the additive model (presence of 1 or 2 copies) (IRR = 1.198, 95% CI = 1.030-1.393, P = 0.019), but was not significant after multiple test correction. Modeling of the haplotypes revealed that the CC haplotype had a significant additive effect for protection against SMA (i.e., reduced risk for development of SMA) after multiple test correction (IRR = 0.823, 95% CI = 0.711-0.952, P = 0.009). Although increased susceptibility to SMA was present in carriers of the GC haplotype (IRR = 1.276, 95% CI = 1.030-1.581, P = 0.026) with an additive effect (IRR = 1.182, 95% CI = 1.018-1.372, P = 0.029), the results did not remain significant after multiple test correction. None of the NCR3 genotypes or haplotypes were associated with all-cause mortality.

CONCLUSIONS

Variation in NCR3 alters susceptibility to malaria and SMA during the acquisition of naturally-acquired malarial immunity. These results highlight the importance of NK cells in the innate immune response to malaria.

Prevalence Rate of Thalassemia Carriers among Individuals with Microcytosis or Hypochromia in Portugal

INTRODUCTION

Microcytosis and hypochromia result from deficient hemoglobin synthesis in red blood cells and are easily detected in a complete blood count test. These conditions are mainly due to iron nutritional deficiency, but may also result from some genetic diseases, such as thalassemia. The aim of this study was to determine the contribution of β- and α-thalassemia to these abnormal hematological phenotypes in a representative sample of adult individuals living in Portugal who participated in the first Portuguese National Health Examination Survey (INSEF).

MATERIAL AND METHODS

Among the 4808 INSEF participants, 204 had microcytosis, hypochromia or both. The corresponding 204 DNAs were screened for changes in the β-globin gene by next-generation sequencing and Sanger sequencing. In addition, α-thalassemia deletions within the α-globin cluster were investigated by Gap-PCR and multiplex ligation-dependent probe amplification.

RESULTS

In this selected subgroup of INSEF participants, 54 had α-thalassemia (26%), predominantly caused by the -α3.7kb deletion, and 22 were β-thalassemia carriers (11%) mainly due to point mutations in the β-globin gene previously known in Portugal.

CONCLUSION

Thalassemia trait is a frequent cause of microcytosis or hypochromia in Portugal since this genetic condition was found in 37% of the investigated cases.

Nonsynonymous amino acid changes in the α-chain of complement component 5 influence longitudinal susceptibility to Plasmodium falciparum infections and severe malarial anemia in kenyan children

Background: Severe malarial anemia (SMA; Hb < 5.0 g/dl) is a leading cause of childhood morbidity and mortality in holoendemic Plasmodium falciparum transmission regions such as western Kenya. Methods: We investigated the relationship between two novel complement component 5 (C5) missense mutations [rs17216529:C>T, p(Val145Ile) and rs17610:C>T, p(Ser1310Asn)] and longitudinal outcomes of malaria in a cohort of Kenyan children (under 60 mos, n = 1,546). Molecular modeling was used to investigate the impact of the amino acid transitions on the C5 protein structure. Results: Prediction of the wild-type and mutant C5 protein structures did not reveal major changes to the overall structure. However, based on the position of the variants, subtle differences could impact on the stability of C5b. The influence of the C5 genotypes/haplotypes on the number of malaria and SMA episodes over 36 months was determined by Poisson regression modeling. Genotypic analyses revealed that inheritance of the homozygous mutant (TT) for rs17216529:C>T enhanced the risk for both malaria (incidence rate ratio, IRR = 1.144, 95%CI: 1.059-1.236, p = 0.001) and SMA (IRR = 1.627, 95%CI: 1.201-2.204, p = 0.002). In the haplotypic model, carriers of TC had increased risk of malaria (IRR = 1.068, 95%CI: 1.017-1.122, p = 0.009), while carriers of both wild-type alleles (CC) were protected against SMA (IRR = 0.679, 95%CI: 0.542-0.850, p = 0.001). Conclusion: Collectively, these findings show that the selected C5 missense mutations influence the longitudinal risk of malaria and SMA in immune-naïve children exposed to holoendemic P. falciparum transmission through a mechanism that remains to be defined.

Fetal-haemoglobin enhancing genotype at BCL11A reduces HbA2 levels in patients with sickle cell anaemia

Understanding the interplay of genetic factors with haemoglobin expression and pathological processes in sickle cell disease is important for pharmacological and gene-therapeutic interventions. In our nascent study cohort of Nigerian patients, we found that three major disease-modifying factors, HbF levels, α-thalassaemia deletion and BCL11A genotype, had expected beneficial haematological effects. A key BCL11A variant, while improving HbF levels (5.7%-9.0%), also led to a small, but significant decrease in HbA2. We conclude that in general, interventions boosting HbF are likely to reduce HbA2 in patients' erythroid cells and that such therapeutic strategies might benefit from a parallel stimulation of HbA2 through independent mechanisms.

Oxidative status in the β-thalassemia syndromes in Sri Lanka; a cross-sectional survey

In the β-thalassemias, oxidative stress, resulting from chronic hemolysis, globin chain imbalance, iron overload and depleted antioxidant defences, likely contributes to cell death, organ damage, anemia, hypoxia and inflammation. We assessed variations in these parameters in β-thalassemia syndromes in Sri Lanka. Between November 2017 and June 2018, we assessed children and adults attending two thalassemia centres in Sri Lanka: 59 patients with HbE β-thalassemia, 50 β-thalassemia major, 40 β-thalassemia intermedia and 13 HbS β-thalassemia. Median age was 26.0 years (IQR 15.3-38.8), 101 (62.3%) were female and 152 (93.8%) of Sinhalese ethnicity. Methemoglobin, plasma hemoglobin, heme and ferritin were measured as sources of oxidants; plasma total antioxidant capacity, haptoglobin, hemopexin and vitamins C and E assessed antioxidant status; plasma thiobarbituric acid reactive substances and 8-hydroxy-2'-deoxyguanosine assessed oxidative damage; hemoglobin, plasma erythropoietin and transferrin receptor assessed anemia and hypoxia and plasma interleukin-6 and C-reactive protein assessed inflammation. Fruit and vegetable intake was determined by dietary recall. Physical fitness was investigated using the 6-min walk test and measurement of handgrip strength. Oxidant sources were frequently increased and antioxidants depleted, with consequent oxidative damage, anemia, hypoxia and inflammation. Biomarkers were generally most abnormal in HbE β-thalassemia and least abnormal in β-thalassemia intermedia but also varied markedly between individuals with the same thalassemia syndrome. Oxidative stress and damage were also more severe in splenectomized patients and/or those receiving iron chelation therapy. Less than 15% of patients ate fresh fruits or raw vegetables frequently, and plasma vitamins C and E were deficient in 132/160 (82.5%) and 140/160 (87.5%) patients respectively. Overall, physical fitness was poor in all syndromes and was likely due to anemic hypoxia. Studies of antioxidant supplements to improve outcomes in patients with thalassemia should consider individual patient variation in oxidative status both between and within the thalassemia syndromes.

Alpha thalassemia, but not βS-globin haplotypes, influence sickle cell anemia clinical outcome in a large, single-center Brazilian cohort

Alpha thalassemia and beta-globin haplotype are considered classical genetic disease modifiers in sickle cell anemia (SCA) causing clinical heterogeneity. Nevertheless, their functional impact on SCA disease emergence and progression remains elusive. To better understand the role of alpha thalassemia and beta-globin haplotype in SCA, we performed a retrospective study evaluating the clinical manifestations of 614 patients. The univariate analysis showed that the presence of alpha-thalassemia -3.7-kb mutation (αα/-α and -α/-α) decreased the risk of stroke development (p = 0.046), priapism (p = 0.033), and cholelithiasis (p = 0.021). Furthermore, the cumulative incidence of stroke (p = 0.023) and cholelithiasis (p = 0.006) was also significantly lower for patients carrying the alpha thalassemia -3.7-kb mutation. No clinical effects were associated with the beta-globin haplotype analysis, which could be explained by the relatively homogeneous haplotype composition in our cohort. Our results reinforce that alpha thalassemia can provide protective functions against hemolysis-related symptoms in SCA. Although, several genetic modifiers can impact the inflammatory state of SCA patients, the alpha thalassemia mutation remains one of the most recurrent genetic aberration and should therefore always be considered first.

Co-Inheritance of alpha-thalassemia and sickle cell disease in a cohort of Angolan pediatric patients

The aim of this study was to explore the association between alpha-thalassemia, fetal hemoglobin, hematological indices, and clinical adverse events in Angolan sickle cell disease pediatric patients. A total of 200 sickle cell disease (SCD) children were sampled in Luanda and Caxito. A venous blood sample was collected and used for hematological analyses, fetal hemoglobin quantification, and genotyping of 3.7 kb alpha-thalassemia deletion by GAP-PCR. The frequency of the 3.7 kb alpha-thalassemia deletion in homozygosity was 12.5% and in heterozygosity was 55.0%. An increase in alpha-thalassemia frequency was observed in children older than 5 years old (11.7% vs. 13.00%). Furthermore, 3.7 kb alpha-thalassemia deletion homozygotes had a significantly higher age of the first manifestation, lower number of blood transfusions by year, higher hemoglobin, lower mean corpuscular volume, mean corpuscular hemoglobin, and lower hemolytic rate observed by a lower number of reticulocytes count. There were no differences in fetal hemoglobin between the three genotypes. Moreover, the number of stroke events, osteomyelitis, splenomegaly, splenectomy, and hepatomegaly were lower when alpha-thalassemia was co-inherited. For the first time in Angolan population, the effect of alpha-thalassemia deletion in sickle cell disease was analyzed and results reinforce that this trait influences the hematological and clinical aspects and produces a milder phenotype.

Biomarkers and genetic modulators of cerebral vasculopathy in sub-Saharan ancestry children with sickle cell anemia

We investigated biomarkers and genetic modulators of the cerebral vasculopathy (CV) subphenotype in pediatric sickle cell anemia (SCA) patients of sub-Saharan African ancestry. We found that one VCAM1 promoter haplotype (haplotype 7) and VCAM1 single nucleotide variant rs1409419_T were associated with stroke events, stroke risk, as measured by time-averaged mean of maximum velocity in the middle cerebral artery, and with high serum levels of the hemolysis biomarker lactate dehydrogenase. Furthermore, VCAM-1 ligand coding gene ITGA4 variants rs113276800_A and rs3770138_T showed a positive association with stroke events. An additional positive relationship between a genetic variant and stroke risk was observed for ENPP1 rs1044498_A. Conversely, NOS3 variants were negatively associated with silent cerebral infarct events (VNTR 4b_allele and haplotype V) and CV globally (haplotype VII). The -alpha^3.7kb-thal deletion did not show association with CV. However, it was associated with higher red blood cell and neutrophil counts, and lower mean corpuscular volume, mean corpuscular hemoglobin and red cell distribution width. Our results underline the importance of genetic modulators of the CV sub-phenotype and their potential as SCA therapeutic targets. We also propose that a biomarker panel comprising biochemical, hematological, imaging and genetic data would be instrumental for CV prediction, and prevention.

Prevalence and Genetic Analysis of α- and β-Thalassemia and Sickle Cell Anemia in Southwest Iran

This prospective study assessed the prevalence and genetic analysis of α- and β-thalassemia and sickle cell anemia (SCA) in Southwest Iran. Hematological indices were measured in 17,581 couples living in Khuzestan Province, Southwest Iran. Individuals with mean corpuscular volume <80, mean corpuscular hemoglobin <27, hemoglobin A2 ≥3/5 were considered as β-thalassemia traits. Prevalence of minor β-thalassemia, α-thalassemia, SCA, iron deficiency anemia, and silent thalassemia were respectively identified in 995 (5.6%), 1169 (6.65%), 1240 (7.05%), 911 (5.18%), and 1134 (6.45%) individuals using a multiplex amplification refractory mutation system, and direct DNA sequencing of globin genes. Three codons IVS-II-1 (G → A; 26%; n = 13), IVS-I-1 (G → T; 16%; n = 8), and IVS-I-110 (G → A; 14%; n = 7) were the most frequent mutants and IVS-II-1 was the most common β-thalassemia mutation. Also, based on a gap-polymerase chain reaction assay, genotype frequencies of α-globin mutations were -α^{3.7 kb} (50%; n = 25), Med/αα^thal (12%; n = 6), and -α4.2/αα (10%; n = 5), which were the most frequent deletion mutants (72% in total). The most common deletion (50%) was -α^{3.7 kb}. Our data suggest that the population of Southwest Iran is at high risk of α- and β-thalassemia caused by these deletion mutants and SCA. Our findings will be useful for developing an efficient control program and genetic counseling.

Genetic modulators of fetal hemoglobin expression and ischemic stroke occurrence in African descendant children with sickle cell anemia

Sickle cell anemia (SCA) is an autosomal recessive monogenic disease with significant clinical variability. Cerebrovascular disease, particularly ischemic stroke, is one of the most severe complications of SCA in children. This study aimed to investigate the influence of genetic variants on the levels of fetal hemoglobin (Hb F) and biochemical parameters related with chronic hemolysis, as well as on ischemic stroke risk, in ninety-one unrelated SCA patients, children of sub-Saharan progenitors. Our results show that a higher Hb F level has an inverse relationship with the occurrence of stroke, since the group of patients who suffered stroke presents a significantly lower mean Hb F level (5.34 ± 4.57% versus 9.36 ± 6.48%; p = 0.024). Furthermore, the co-inheritance of alpha-thalassemia improves the chronic hemolytic pattern, evidenced by a decreased reticulocyte count (8.61 ± 3.58% versus 12.85 ± 4.71%; p < 0.001). In addition, our findings have confirmed the importance of HBG2 and BCL11A loci in the regulation of Hb F expression in sub-Saharan African SCA patients, as rs7482144_A, rs11886868_C, and rs4671393_A alleles are significantly associated with a considerable increase in Hb F levels (p = 0.019, p = 0.026, and p = 0.028, respectively). Concerning KLF1, twelve different variants were identified, two of them novel. Seventy-three patients (80.2%) presented at least one variant in this gene. However, no correlation was observed between the presence of these variants and Hb F level, severity of hemolysis, or stroke occurrence, which is consistent with their in silico-predicted minor functional consequences. Thus, we conclude that the prevalence of functional KLF1 variants in a sub-Saharan African background does not seem to be relevant to SCA clinical modulation.

Molecular characteristics of α+-thalassemia (3.7 kb deletion) in Southeast Asia: Molecular subtypes, haplotypic heterogeneity, multiple founder effects and laboratory diagnostics

OBJECTIVE

The 3.7 kb deletion (-α^3.7) is the most common form of α⁺-thalassemia found in multiple populations which can be classified into three subtypes. In order not to mis-identify it, the molecular information within each population is required. We have addressed this in northeast Thai and Laos populations.

METHODS

Screening for α⁺-thalassemia was initially done on 1192 adult Thai subjects. In addition, 77 chromosomes of Thai newborns and 26 chromosomes of Laos with -α^3.7 α⁺-thalassemia were also examined. All subjects were screened for -α^3.7 α⁺-thalassemia and subtyped by PCR-RFLP assay. Exact deletion breakpoint of each -α^3.7 subtype was determined by DNA sequencing. α-Globin gene haplotypes were determined.

RESULTS

The proportions of -α^3.7 subtypes found in 216 Thai -α^3.7 chromosomes were 94.9% for -α^3.7I, 4.2% for α^3.7II and 0.9% for -α^3.7III. All 26 Laos -α^3.7 chromosomes were of -α^3.7I variety. At least six α-globin gene haplotypes were associated with the -α^3.7I α⁺-thalassemia.

CONCLUSION

All -α^3.7 subtypes were observed among Southeast Asian population. Haplotype analysis indicated a multiple origin of this common disorder in the region. A multiplex PCR assay has been developed for simultaneous detection of all subtypes of -α^3.7 α⁺-thalassemia as well as other α⁺-thalassemia found in the region including -α^4.2 α⁺-thalassemia, Hb Constant Spring and Hb Paksé.

Alpha-Thalassemia in North Morocco: Prevalence and Molecular Spectrum

Unlike the other hemoglobinopathies, few researches have been published concerning α-thalassemia in Morocco. The epidemiological features and the mutation spectrum of this disease are still unknown. This regional newborn screening is the first to study α-thalassemia in the north of Morocco. During the period from January 2015 to December 2016, 1658 newborns umbilical blood samples were investigated. Suspected newborns were screened for α-globin defects using Gap-PCR and Multiplex Ligation-dependent Probe Amplification technique. The prevalence of α-thalassemia, its mutation spectrum, and its allelic frequencies were described for the first time in Morocco. Six different α-globin genetic disorders were detected in 16 neonates. This screening valued the prevalence of α-thalassemia in the studied population at 0.96% and showed the wide mutation spectrum and the heterogeneous geographical distribution of the disease. A high rate of carriers was observed in Laouamra, a rural commune in Larache province. Heterogeneity of α-globin alleles in Morocco explains the high variability of α-thalassemia severity. This diversity reflects the anthropological history of the country. These results would contribute to the prevention of thalassemia in Morocco directing the design of a nationwide screening strategy and awareness campaign.

Biological impact of α genes, β haplotypes, and G6PD activity in sickle cell anemia at baseline and with hydroxyurea

Sickle cell anemia (SCA), albeit monogenic, has heterogeneous phenotypic expression, mainly related to the level of hemoglobin F (HbF). No large cohort studies have ever compared biological parameters in patients with major β-globin haplotypes; ie, Senegal (SEN), Benin (BEN), and Bantu/Central African Republic (CAR). The aim of this study was to evaluate the biological impact of α genes, β haplotypes, and glucose-6-phosphate dehydrogenase (G6PD) activity at baseline and with hydroxyurea (HU). Homozygous HbS patients from the Créteil pediatric cohort with available α-gene and β-haplotype data were included (n = 580; 301 females and 279 males) in this retrospective study. Homozygous β-haplotype patients represented 74% of cases (37.4% CAR/CAR, 24.3% BEN/BEN, and 12.1% SEN/SEN). HU was given to 168 cohort SCA children. Hematological parameters were recorded when HbF was maximal, and changes (ΔHU-T0) were calculated. At baseline, CAR-haplotype and α-gene numbers were independently and negatively correlated with Hb and positively correlated with lactate dehydrogenase. HbF was negatively correlated with CAR-haplotype numbers and positively with BEN- and SEN-haplotype numbers. The BCL11A/rs1427407 "T" allele, which is favorable for HbF expression, was positively correlated with BEN- and negatively correlated with CAR-haplotype numbers. With HU treatment, Δ and HbF values were positively correlated with the BEN-haplotype number. BEN/BEN patients had higher HbF and Hb levels than CAR/CAR and SEN/SEN patients. In conclusion, we show that BEN/BEN patients have the best response on HU and suggest that this could be related to the higher prevalence of the favorable BCL11A/rs1427407/T/allele for HbF expression in these patients.

Prognostic factors of disease severity in infants with sickle cell anemia: A comprehensive longitudinal cohort study

In order to identify very early prognostic factors that can provide insights into subsequent clinical complications, we performed a comprehensive longitudinal multi-center cohort study on 57 infants with sickle cell anemia (55 SS; 2 Sβ°) during the first 2 years of life (ClinicalTrials.gov: NCT01207037). Time to first occurrence of a severe clinical event-acute splenic sequestration (ASS), vaso-occlusive (VOC) event requiring hospitalization, transfusion requirement, conditional/ abnormal cerebral velocities, or death-was used as a composite endpoint. Infants were recruited at a mean age of 4.4 ±1 months. Median follow-up was 19.4 months. During the study period, 38.6% of infants experienced ≥1 severe event: 14% ASS, 22.8% ≥ 1 VOC (median age: 13.4 and 12.8 months, respectively) and 33.3% required transfusion. Of note, 77% of the cohort was hospitalized, with febrile illness being the leading cause for admission. Univariate analysis of various biomarkers measured at enrollment showed that fetal hemoglobin (HbF) was the strongest prognostic factor of subsequent severe outcome. Other biomarkers measured at enrolment including absolute neutrophil or reticulocyte counts, expression of erythroid adhesion markers, % of dense red cells, cellular deformability or ϒ-globin genetic variants, failed to be associated with severe clinical outcome. Multivariate analysis demonstrated that higher Hb concentration and HbF level are two independent protective factors (adjusted HRs (95% CI) 0.27 (0.11-0.73) and 0.16 (0.06-0.43), respectively). These findings imply that early measurement of HbF and Hb levels can identify infants at high risk for subsequent severe complications, who might maximally benefit from early disease modifying treatments.

Influence of alpha thalassemia on clinical and laboratory parameters among nigerian children with sickle cell anemia

BACKGROUND

There is paucity of data on the influence of alpha thalassemia on the clinical and laboratory parameters among Nigerian sickle cell anemia (SCA) patients. This study aimed to determine the prevalence of alpha thalassemia and the influence of alpha thalassemia on laboratory parameters and clinical manifestations in a group of young Nigerian SCA patients.

METHODS

This was a cross-sectional retrospective study conducted on 100 patients with SCA and 63 controls. The diagnosis of SCA was confirmed by DNA studies. Alpha thalassemia genotyping was performed by multiplex gap-PCR method. Laboratory parameters including complete blood count, hemoglobin quantitation, serum lactate dehydrogenase (LDH), and bilirubin were determined with standard techniques.

RESULTS

Alpha thalassemia was found in 41 (41.0%) patients compared to 24 (38.1%) controls (P = 0.744), and all were due to the 3.7 κb α-globin gene deletions. Alpha thalassemia was associated with more frequent bone pain crisis, higher hemoglobin concentration, red blood cell count, and HbA₂ level among the patients. On the contrary, patients with alpha thalassemia had lower mean corpuscular volume, mean corpuscular hemoglobin, and white blood cell count (WBC) (P ˂ 0.05). There were 6 (6.0%) patients with leg ulcers, and none of them had alpha thalassemia, P = 0.04.

CONCLUSION

This study confirms that coexistence of alpha thalassemia with SCA significantly influences both the clinical and laboratory manifestations of young Nigerian SCA patients. The coexistence of this genetic modifier is associated with increased bone pain crisis and protects against sickle leg ulcers among the patients.

[Rapid detection of alpha-globin gene αααanti-3.7 triplets with droplet digital PCR]

OBJECTIVE

To establish a rapid method for detection of alpha-globin gene ααα^anti-3.7 based on droplet digital PCR (ddPCR) technique.

METHODS

The differential sequence between the X1 and Y1 box of α1 gene was selected as the amplicon of the target gene with β-actin as the reference gene. The specific primers and TaqMan probes were designed, and then a quantitative method for detecting the copy number was established based on ddPCR technique. The sensitivity and accuracy of the method were evaluated by detecting 28 samples of known genotypes and 60 clinical samples.

RESULTS

The ddPCR-based method accurately identified the genotypes of all the 28 samples with known genotypes and detected 5 cases of αα/ααα^anti-3.7 from the 60 clinical samples, and the results were verified by MLPA. The sensitivity and accuracy of this method were both 100% for detecting alpha-globin gene ααα^anti-3.7.

CONCLUSION

This ddPCR-based method for detecting ααα^anti-3.7 triplet can be applied for population screening and in routine clinical molecular diagnosis with simple operation, rapid analysis and accurate results.

Coinheritance of Hb Bristol-Alesha [β67(E11)Val→Met; HBB: c.202G>A] and the α212 Patchwork Allele in a Brazilian Child with Severe Congenital Hemolytic Anemia

Hb Bristol-Alesha [HBB: c.202G>A; β 67 Val>Met] is a rare structural variant of hemoglobin (Hb) resulting from a GTG>ATG substitution at codon 67 of the β-globin gene that leads to the replacement of valine by methionine in the corresponding position of the β-globin chain. The methionine residue is subsequently modified to aspartic acid [β67(E11)Val-Met→Asp], possibly by autoxidation mechanisms. This substitution prevents normal non-polar binding of Val67 to the heme group, resulting in molecular instability and severe hemolysis. We identified Hb Bristol-Alesha (in the heterozygous state), as the cause of severe congenital hemolytic anemia in an 11-month-old girl of mixed (native Indian and European) ethnic origin from the Midwestern region of Brazil, whose parents were clinically and hematologically normal. The mutation on the β-globin gene was found to have been coinherited with the α212 patchwork allele.

Anaemia in hospitalised preschool children from a rural area in Mozambique: a case control study in search for aetiological agents

Background

Young children bear the world’s highest prevalence of anaemia, the majority of which is of multifactorial aetiology, which in turn hampers its successful prevention. Even moderate degrees of anaemia are associated with increased mortality and morbidity. Despite this evidence, there is a lack of effective preventive programs and absence of consensus in the safety of iron supplementation in malaria areas, which reflects the poor understanding of the contribution of different aetiologies to anaemia. In order to reduce the anaemia burden in the most vulnerable population, a study to determine the aetiology of anaemia among pre-school Mozambican children was performed.

Methods

We undertook a case–control study of 443 preschool hospitalized children with anaemia (haemoglobin concentration <11 g/dl) and 289 community controls without anaemia. Inclusion criteria were: age 1–59 months, no blood transfusion in the previous month, residence in the study area and signed informed consent. Both univariable and multivariable logistic regression analyses were performed to identify factors associated with anaemia and adjusted attributable fractions (AAF) were estimated when appropriate.

Results

Malaria (adjusted odds ratio (AOR) = 8.39, p < 0.0001; AAF = 37%), underweight (AOR = 8.10, p < 0.0001; AAF = 43%), prealbumin deficiency (AOR = 7.11, p < 0.0001; AAF = 77%), albumin deficiency (AOR = 4.29, p = 0.0012; AAF = 30%), HIV (AOR = 5.73, p = 0.0060; AAF = 18%), and iron deficiency (AOR = 4.05, p < 0.0001; AAF = 53%) were associated with anaemia. Vitamin A deficiency and α-thalassaemia were frequent (69% and 64%, respectively in cases) but not independently related to anaemia. Bacteraemia (odds ratio (OR) = 8.49, p = 0.004), Parvovirus-B19 (OR = 6.05, p = 0.017) and Epstein-Barr virus (OR = 2.10, p = 0.0015) infections were related to anaemia only in the unadjusted analysis. Neither vitamin B12 deficiency nor intestinal parasites were associated with anaemia. Folate deficiency was not observed.

Conclusions

Undernutrition, iron deficiency, malaria, and HIV are main factors related to anaemia in hospitalised Mozambican preschool children. Effective programs and strategies for the prevention and management of these conditions need to be reinforced. Specifically, prevention of iron deficiency that accounted in this study for more than half of anaemia cases would have a high impact in reducing the burden of anaemia in children living under similar conditions. However this deficiency, a common preventable and treatable condition, remains neglected by the international public health community.

The Problem of Borderline Hemoglobin A2 Levels in the Screening for β-Thalassemia Carriers in Sardinia

BACKGROUND

The increase in HbA2 is the most important parameter for the identification of thalassemia carriers. However, in routine screening for hemoglobinopathies, some cases are difficult to classify because the level of HbA2 is not typically elevated. In this work, we report the results of a molecular investigation on a cohort of subjects with borderline HbA2.

METHODS

All subjects with a β-thalassemia carrier partner and a borderline percentage level of HbA2 were investigated for the presence of a pathological mutation in the β-globin gene. All negative subjects were screened for both the KLF1 mutation and the presence of ααα/ or αααα/ alleles. The subjects with reduced MCV and/or MCH were also screened for deletional and nondeletional α-globin gene defects.

RESULTS

Various β-globin mutations and KLF1 gene defects are the most common genetic determinants responsible for this phenotype in our population.

CONCLUSION

KLF1 mutations are important in a screening program for hemoglobinopathies. An increase in HbF in association with borderline HbA2 levels is a useful but not exclusive marker that suggests the investigation of this gene. On the basis of our findings, we are able to suggest the molecular procedure to use in a population characterized by a high prevalence of thalassemia carriers.

Hemoglobin A2 values in sickle cell disease patients quantified by high performance liquid chromatography and the influence of alpha thalassemia

Background

In sickle cell disease, the quantification of Hb A₂ is important for the differential diagnosis between sickle cell anemia (Hb SS) and Hb S/β⁰-thalassemia.

Objective

To determine Hb A₂ levels as quantified by high performance liquid chromatography in patients with sickle cell anemia (Hb SS) and with the SC hemoglobinopathy, with or without concomitant alpha thalassemia.

Methods

This is a retrospective study of 242 children aged between two and six years with diagnoses of Hb SS or Hb SC. The hemoglobin was evaluated using high performance liquid chromatography and alpha thalassemia [3.7 kb deletion (−α^3.7)] was detected by polymerase chain reaction. Patients were classified as homozygous (−α^3.7/−α^3.7), heterozygous (−α^3.7/α), or homozygous wild-type. Analysis of variance was used to compare the mean Hb A₂ values between the alpha thalassemia groups.

Results

The mean (± standard deviation) Hb A₂ concentrations in the Hb SS group (n = 135) was 3.68 ± 0.65%. The mean values for individuals with Hb SS and heterozygous (n = 28) or homozygous for alpha thalassemia (n = 3) were 3.98 ± 0.64% and 4.73 ± 0.25%, respectively. The mean Hb A₂ of all the Hb SC patients (n = 107) was 4.01 ± 0.507 with 4.29 ± 0.41% and 4.91 ± 0.22% in individuals heterozygous (n = 23) and homozygous for alpha thalassemia (n = 7), respectively. All patients homozygous for alpha thalassemia had Hb A₂ levels above 3.5%. However, Hb A₂ values above 5.2% were seen in patients with Hb SS and Hb SC, independently of alpha thalassemia.

Conclusion

Hb A₂ levels are elevated in patients with Hb S or Hb C, and are directly influenced by the alpha thalassemia genotypes.

Prevalence of hemoglobinopathies in school children: the importance of using confirmatory methods

<p>The hemoglobinopathies are included among the most common genetic diseases in the world. In Brazil, hemoglobinopathies are related to the diversity of racial backgrounds and the degree of interbreeding. The study focused on the prevalence of hemoglobinopathies using conventional and confirmatory laboratory tests in children from public schools in Ribeirão Preto-SP. The study involved the participation of 427 children between six and nine years of age. Hematologic evaluation, hemoglobin electrophoresis on cellulose acetate at alkaline pH, quantification of hemoglobin fractions by high performance liquid chromatography (HPLC) and detection of -α^3.7 deletion for α thalassemia by polymerase chain reaction were performed. The results of hemoglobin electrophoresis on cellulose acetate and HPLC of the children studied showed the presence of 30 children (7%) with hemoglobinopathies. Eleven children presented results indicating suspicion of S/β-thalassemia; their parents and/or siblings were evaluated and confirmed the presence of only Hb S. The analysis of deletion -α^3.7to characterize α-thalassemias sampling performed on 207 participants identified 26 children (12.6%) with deletion -α^3.7. Thus, 54 (12.6%) of the children studied present this genetic alteration. For the detection of α-thalassemias it is necessary to use confirmatory methods such as molecular analysis and evaluation of family members in doubtful cases to facilitate genetic counseling in families, in which deletion -α^3.7 is more frequent in Brazil.</p>

Genetic determinants of β-thalassemia intermedia in Pakistan

This study covers the molecular characterization of clinically diagnosed β-thalassemia intermedia (β-TI) patients in Pakistan. Blood samples of β-TI patients were collected from all four provinces of Pakistan throughout the period of 2011-2013. The study was carried out using allele-specific primers through polymerase chain reaction or sequencing to determine both α- and β-thalassemia (α- and β-thal) mutations, and restriction enzymes for the characterization of β-globin gene arrangements. In a total of 63 patients, the IVS-I-5 (G > C) was the most frequent mutation (33.88%). The codon 30 (G > A) and IVS-II-1 (T > C) mutations were found only in the Punjabi ethnic group, while the codon 30 (G > C) and Hb S (HBB: c.20A > T) mutations were found only in the Pashtoon and Sindhi ethnic groups, respectively. In case of α-globin genotypes, 44 patients were normal (αα/αα), six patients carried the αα/-α(3.7) genotype, 12 patients carried the -α(3.7)/-α(3.7) genotype, while one patient had the αα/ααα(anti 3.7) genotype. We found that haplotype I was the most frequent, mostly associated with the codons 8/9 (+G) mutation, while the Saudi haplotype was found only with Hb S.

Altered erythropoiesis and iron metabolism in carriers of thalassemia

The thalassemia syndromes (α- and β-thalassemia) are the most common and frequent disorders associated with ineffective erythropoiesis. Imbalance of α- or β-globin chain production results in impaired red blood cell synthesis, anemia, and more erythroid progenitors in the blood stream. While patients affected by these disorders show definitive altered parameters related to erythropoiesis, the relationship between the degree of anemia, altered erythropoiesis, and dysfunctional iron metabolism has not been investigated in both α-thalassemia carriers (ATC) and β-thalassemia carriers (BTC). Here, we demonstrate that ATC have a significantly reduced hepcidin and increased soluble transferrin receptor levels but relatively normal hematological findings. In contrast, BTC have several hematological parameters significantly different from controls, including increased soluble transferrin receptor and erythropoietin levels. These changes in both groups suggest an altered balance between erythropoiesis and iron metabolism. The index sTfR/log ferritin and (hepcidin/ferritin)/sTfR are, respectively, increased and reduced relative to controls, proportional to the severity of each thalassemia group. In conclusion, we showed in this study, for the first time in the literature, that thalassemia carriers have altered iron metabolism and erythropoiesis.

α-Thalassemia does not seem to influence erythrocyte deformability in sickle cell trait carriers

Studies dealing with rheological red blood cell (RBC) behavior in sickle cell trait carriers are scarce. Moreover, the association with α-thalassemia (α-thal), which also modifies erythrocyte behavior, has not always been taken into account. We analyzed erythrocyte deformability by means of a shear stress diffractometer, along with hematological and biochemical parameters (glucose and plasma lipids), given their possible influence on erythrocyte deformability, in 14 sickle cell trait carriers and 23 healthy controls. Nine patients were also α-thal carriers and five were not. Among the thalassemia carriers, eight were heterozygous and one was homozygous. When compared with controls, sickle cell trait carriers showed no differences for any of the biochemical parameters analyzed (p > 0.05), but significantly lower hemoglobin (Hb) (p = 0.003), mean corpuscular volume (MCV) and mean corpuscular Hb (MCH) (p < 0.001) levels, although no differences in erythrocyte deformability were observed at any of the shear stresses tested (p > 0.05). When comparing sickle cell trait carriers, with and without α-thal, no differences in erythrocyte deformability were observed (p > 0.05), in spite of the former showing lower MCV and MCH (p < 0.05) levels. Carriers of α-thal had lower Hb S [β6(A3)Glu → Val; HBB: c.20A > T] levels (p = 0.013) than non carriers. The existence of a compensating mechanism seems reasonable because, despite presenting lower erythrocyte indices, which could worsen erythrocyte deformability, this rheological property improves when the percentage of Hb S is lower.

Genetic variation in CD36, HBA, NOS3 and VCAM1 is associated with chronic haemolysis level in sickle cell anaemia: a longitudinal study

Chronic haemolysis stands out as one of the hallmarks of sickle cell anaemia, a clinically heterogeneous autosomal recessive monogenic anaemia. However, the genetic architecture of this sub-phenotype is still poorly understood. Here, we report the results of an association study between haemolysis biomarkers (serum LDH, total bilirubin and reticulocyte count) and the inheritance of 41 genetic variants of ten candidate genes in a series of 99 paediatric SS patients (median current age of 9.9 yr) followed up in two general hospitals in Greater Lisboa area (median follow-up per patient of 5.0 yr). Although in a large number of tests a seemingly significant (i.e. P < 0.05) association was observed, the following ones were confirmed upon correction for multiple comparisons: (i) an increased serum LDH level was associated with haplotype 7 within VCAM1 gene; (ii) a lower total bilirubin was associated with the 3.7-kb deletion at HBA gene, rs2070744_T allele at NOS3 gene, and haplotype 9 within VCAM1 promoter; and (iii) a diminished reticulocyte count was associated with the 3.7-kb deletion at HBA, whereas an increased count was associated with rs1984112_G allele at CD36 gene. On the whole, our findings suggest a complex genetic architecture for the sickle cell anaemia haemolysis process involving multiple pathways, namely control of vascular cell adhesion, NO synthesis and erythrocyte volume and haemoglobinisation.

Challenges in the diagnosis of iron deficiency in children exposed to high prevalence of infections

BACKGROUND

While WHO guidelines recommend iron supplements to only iron-deficient children in high infection pressure areas, these are rarely implemented. One of the reasons for this is the commonly held view that iron supplementation increases the susceptibility to some infectious diseases including malaria. Secondly, currently used markers to diagnose iron deficiency are also modified by infections. With the objective of improving iron deficiency diagnosis and thus, its management, we evaluated the performance of iron markers in children exposed to high infection pressure.

METHODOLOGY/PRINCIPAL FINDINGS

Iron markers were compared to bone marrow findings in 180 anaemic children attending a rural hospital in southern Mozambique. Eighty percent (144/180) of the children had iron deficiency by bone marrow examination, 88% (155/176) had an inflammatory process, 66% (119/180) had moderate anaemia, 25% (45/180) severe anaemia and 9% (16/180) very severe anaemia. Mean cell haemoglobin concentration had a sensitivity of 51% and specificity of 71% for detecting iron deficiency. Soluble transferrin receptor (sTfR) and soluble transferrin receptor/log ferritin (TfR-F) index (adjusted by C reactive protein) showed the highest areas under the ROC curve (AUC(ROC)) (0.75 and 0.76, respectively), and were the most sensitive markers in detecting iron deficiency (83% and 75%, respectively), but with moderate specificities (50% and 56%, respectively).

CONCLUSIONS/SIGNIFICANCE

Iron deficiency by bone marrow examination was extremely frequent in these children exposed to high prevalence of infections. However, even the best markers of bone marrow iron deficiency did not identify around a quarter of iron-deficient children. Tough not directly extrapolated to the community, these findings urge for more reliable, affordable and easy to measure iron indicators to reduce the burden of iron deficiency anaemia in resource-poor settings where it is most prevalent.

Prevalence of α-thalassemia 3.7 kb deletion in the adult population of Rio Grande do Norte, Brazil

α-Thalassemia, arising from a defect in α-globin chain synthesis, is often caused by deletions involving one or both of the α-genes on the same allele. With the aim of investigating the prevalence of α-thalassemia 3.7 kb deletion in the adult population of Rio Grande do Norte, 713 unrelated individuals, between 18 and 59 years-of-age, were analyzed. Red blood cell indices were electronically determined, and A₂ and F hemoglobins evaluated by HPLC. PCR was applied to the molecular investigation of α-thalassemia 3.7 kb deletion. Eighty (11.2%) of the 713 individuals investigated presented α-thalassemia, of which 79 (11.1%) were heterozygous (-α^3.7/αα) deletions and 1 (0.1%) homozygous (-α^3.7/-α^3.7). Ethnically, heterozygous deletions were higher (24.8%) in Afro-Brazilians. Comparison of hematological parameters between individuals with normal genotype and those with heterozygous α⁺-thalassemia showed a statistically significant difference in the number of erythrocytes (p < 0.001), MCV (p < 0.001), MCH (p < 0.001) and Hb A₂ (p = 0.007). This study is one of the first dedicated to investigating α-thalassemia 3.7 kb deletion in the population of the State Rio Grande do Norte state. Results obtained demonstrate the importance of investigating this condition in order to elucidate the causes of microcytosis and hypochromia.

Molecular mechanisms of a novel β-thalassaemia mutation due to the duplication of tetranucleotide 'AGCT' at the junction IVS-II/exon 3

We report a new β-thalassaemia allele detected in a young Italian woman, suffering with mild non-haemolytic anaemia (Hb < 10 g/dL) and not showing Hb variant or Heinz bodies. The allele is characterised by duplication of tetranucleotide 'AG/CT' (+1344/+1347) including the invariant dinucleotide 'AG' of IVS-II acceptor splicing site and the first two nucleotides of codon 105. β-Globin complementary DNA (cDNA) sequencing did not reveal any mutation and qualitative analysis of the reverse transcription PCR reaction showed that only the proximal 3' splice site present in the duplicated gene is used giving race to an anomalous messenger RNA (mRNA) present in trace (1.5 %) because, most probably, rapidly degraded. In the anomalous mRNA, the insertion causes a frameshift and synthesis of an abnormal truncated β-chain (139 residues), unable to form Hb variant because of the severe conformational changes. The duplication might have arisen from secondary structures generated by quasi-palindromic sequence 5'-CCCA(C)AG/CT(CC)TGGG-3'. Restriction fragment length polymorphism analysis for the β-globin haplotype and familiar segregation analysis indicated that the mutant β-globin gene was associated with the haplotype V.

Application of diagnostic methods and molecular diagnosis of hemoglobin disorders in Khuzestan province of Iran

BACKGROUND:

The hemoglobinopathies refer to a diverse group of inherited disorders characterized by a reduced synthesis of one or more globin chains (thalassemias) or the synthesis of structurally abnormal hemoglobin (Hb). The thalassemias often coexist with a variety of structural Hb variants giving rise to complex genotypes and an extremely wide spectrum of clinical and hematological phenotypes. Hematological and biochemical investigations and family studies provide essential clues to the different interactions and are fundamental to DNA diagnostics of the Hb disorders. Although DNA diagnostics have made a major impact on our understanding and detection of the hemoglobinopathies, DNA mutation testing should never be considered a shortcut or the test of first choice in the workup of a hemoglobinopathy.

MATERIALS AND METHODS:

A careful three-tier approach involving: (1) Full blood count (2) Special hematological tests, followed by (3) DNA mutation analysis, provides the most effective way in which to detect primary gene mutations as well as gene-gene interactions that can influence the overall phenotype. With the exception of a few rare deletions and rearrangements, the molecular lesions causing hemoglobinopathies are all identifiable by PCR-based techniques. Furthermore, each at-risk ethnic group has its own combination of common Hb variants and thalassemia mutations. In Iran, there are many different forms of α and β thalassemia. Increasingly, different Hb variants are being detected and their effects per se or in combination with the thalassemias, provide additional diagnostic challenges.

RESULTS:

We did step-by-step diagnosis workup in 800 patients with hemoglobinopathies who referred to Research center of Thalassemia and Hemoglobinopathies in Shafa Hospital of Ahwaz Joundishapour University of medical sciences, respectively. We detected 173 patients as iron deficiency anemia (IDA) and 627 individuals as thalassemic patients by use of different indices. We have successfully detected 75% (472/627) of the β-thalassemia mutations by using amplification refractory mutation system (ARMS) technique and 19% (130/627) of the β-thalassemia mutations by using Gap-PCR technique and 6% (25/627) as Hb variants by Hb electrophoresis technique. We did prenatal diagnosis (PND) for 176 couples which had background of thalassemia in first pregnancy. Result of PND diagnosis in the first trimester was 35% (62/176) affected fetus with β-thalassemia major and sickle cell disease that led to termination of the pregnancy.

CONCLUSION:

Almost all hemoglobinopathies can be detected with the current PCR-based assays with the exception of a few rare deletions. However, the molecular diagnostic service is still under development to try and meet the demands of the population it serves. In the short term, the current generation of instruments such as the capillary electrophoresis systems, has greatly simplified DNA sequence analysis.

Two new hemoglobin variants: Hb Aix-Les-Bains [β5(A2)Pro→Leu; HBB:c.17 C>T] and Hb Dubai [α122(H5)His→Leu (α2); HBA2:c.368 A>T]

We report two new hemoglobin (Hb) variants; one causing an impairment of the N-terminal glycation of the β-globin chain and the other a hematological phenotype of α-thalassemia (α-thal). The first variant is Hb Aix-les-Bains [β5(A2)Pro→Leu] and the second Hb Dubai [α122(H5)His→Leu (α2)]. These two new Hb variants were detected by chromatographic and electrophoretic methods and characterized by molecular studies. Hb Dubai gives an α-thalassemic phenotype and should be routinely detected for preventing severe Hb H disease in couples at-risk for α-thal.

Genotype-phenotype relationship of the δ-thalassemia and Hb A(2) variants: observation of 52 genotypes

The increase of Hb A(2) (α2δ2) beyond the upper limit [2.0-2.2/3.3-3.4% of the total hemoglobin (Hb)] is an invaluable tool in the hematological screening of β-thalassemia (β-thal) carriers. Factors decreasing Hb A(2) percentages can hinder correct diagnosis. In order to analyze the genotype-phenotype relationship, we characterized δ-, β- and α-globin genotypes in 190 families where the probands had Hb A(2) values of ≤2.0% or were β-thal heterozygotes with normal Hb A(2) levels. Hb A(2) was measured with cation exchange high performance liquid chromatography (HPLC). Mutations were detected with allele-specific methods or DNA sequencing; two multiplex-ARMS (amplification refractory mutation system) assays were set up. The molecular basis underlying the decrease in Hb A(2) was extremely heterogeneous. Nineteen δ-globin alleles (Hb A(2)-S.N. Garganico was new) were detected; their interaction with α- or β-globin alleles (10 and eight, respectively) led us to observe 52 genotypes in 261 carriers. The type of δ-globin mutations, the relative genotypes, the interaction with α(0)-thal traits, are the most important factors in decreasing the Hb A(2) percentage. These results are extremely useful in addressing the molecular diagnosis of hemoglobinopathies and thalassemias.

Enhanced activation of autophagy in β-thalassemia/Hb E erythroblasts during erythropoiesis

Erythropoiesis in β-thalassemia patients is ineffective, primarily because of death of the erythroid progenitor cells at the polychromatic normoblast stage. While it is known that autophagy plays a critical role during erythropoiesis by removing organelles from erythroid cells during terminal differentiation, its role in erythroid cells whose function is impaired remains to be explored. To investigate this, CD34+ erythroid progenitor cells from normal controls and β-thalassemia/Hb E patients were isolated from peripheral blood and cultured under conditions driving differentiation into an erythroid lineage, and levels of autophagy and apoptosis were analyzed both directly and after biochemical manipulation with L: -asparagine. A significantly higher level of autophagy was seen in β-thalassemia/Hb E erythroblasts as compared to normal control erythroblasts during erythropoiesis. Interestingly, this activation was mediated in part by the presence of high levels of Ca(2+) as modulation of Ca(2+) levels significantly reduced the level of autophagy in these cells. Inhibition of autophagic flux in normal erythroblasts significantly increased apoptosis in normal erythroblasts, but not in thalassemic erythroblasts, although sensitivity to autophagic flux inhibition was restored by reduction of Ca(2+) levels. These results suggest that high levels of autophagy in β-thalassemia/HbE erythroblasts may contribute to the increased levels of apoptosis that lead to ineffective erythropoiesis in β-thalassemia/Hb E erythroblasts.

Prevalence of common α-thalassemia determinants in south Brazil: Importance for the diagnosis of microcytic anemia

Alpha thalassemia has not been systematically investigated in Brazil. In this study, 493 unrelated individuals from the southernmost Brazilian state of Rio Grande do Sul were screened for deletional forms of α-thalassemia. One hundred and one individuals had microcytic anemia (MCV < 80 fL) and a normal hemoglobin pattern (Hb A ₂ < 3.5% and Hb F < 1%). The subjects were screened for - α^3.7 , - α^4.2 , - α^20.5 , — ^SEA and — ^MED deletions but only the - α^3.7 allele was detected. The - α^3.7 allele frequency in Brazilians of European and African ancestry was 0.02 and 0.12, respectively, whereas in individuals with microcytosis the frequency was 0.20. The prevalence of α-thalassemia was significantly higher in individuals with microcytosis than in healthy individuals (p = 0.001), regardless of their ethnic origin. There were also significant differences in the hematological parameters of individuals with - α^3.7 / αα, - α^3.7 /- α^3.7 and β-thalassemia trait compared to healthy subjects. These data suggest that α-thalassemia is an important cause of microcytosis and mild anemia in Brazilians.

A mechanism of ineffective erythropoiesis in β-thalassemia/Hb E disease

BACKGROUND

Cells respond to stress stimuli through a number of response pathways, of which one of the most important and well characterized is the unfolded protein response. Despite a large body of work which suggests that stress in erythroblasts may play a pivotal role in the pathogenesis of beta-thalassemia/Hb E disease, this pathway remains uninvestigated.

DESIGN AND METHODS

Day 10 erythroblasts from normal controls and beta-thalassemia/Hb E patients were subjected to internal (treatment with tunicamycin) and external (serum and growth factor withdrawal) stress stimuli and the activation of the unfolded protein response pathway was investigated.

RESULTS

Normal erythroblasts responded to both internal and external stress by activating the unfolded protein response (UPR) pathway while in contrast, erythroblasts from beta-thalassemia/Hb E patients only showed activation of the unfolded protein response pathway in response to internal stress. This was reflected by a markedly increased induction of apoptosis in serum and growth factor deprived beta-thalassemia/Hb E erythroblasts as compared to control cells. Modulation of the levels of intracellular Ca(2+) in thalassemic erythroblasts restored UPR activation during serum deprivation and significantly reduced the level of serum deprivation induced apoptosis to control levels.

CONCLUSIONS

These results suggest the failure of thalassemic erythroblasts to cope with cellular stress caused by an impaired UPR function as a result of high Ca(2+) levels may exacerbate thalassemic cell death during erythropoiesis.