Anemia in Patients with Coinherited Thalassemia and Glucose-6-Phosphate Dehydrogenase Deficiency

Thalassemia and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency are genetic disorders that cause hemolytic anemia. In areas with high frequencies of both hematological disorders, coinheritance of G-6-PD deficiency with thalassemia can be found. Whether G-6-PD deficiency, coinherited with thalassemia, enhances severe anemia is still unclear. Hematological parameters between thalassemia carriers with G-6-PD deficiency and those without G-6-PD deficiency were compared. The G-6-PD deficiency was diagnosed in 410 blood samples from thalassemia patients using a fluorescent spot test. The levels of hemoglobin (Hb), packed cell volume (PCV), mean corpuscular volume (MCV) and Hb A₂/Hb E [β26(B8)Glu→Lys; HBB: c.79G>A] were measured using an automated blood counter and high performance liquid chromatography (HPLC), respectively. The G-6-PD deficiency was found in 37 samples (9.02%). Mean levels of Hb, PCV, MCV and Hb A₂/E were similar between the two groups. Thus, G-6-PD deficiency did not enhance red blood cell pathology or induce more anemic severity in thalassemia patients.     

Genetic Polymorphisms of Glucose-6-Phosphate Dehydrogenase in Lagos,Nigeria

Glucose-6-phosphate dehydrogenase (G6PD) is an essential enzyme in the pentose phosphate pathway that prevents oxidative damage to cells. This study determined the genotypic and allelic frequencies of G6PD G202A and A376G and also investigated correlation between G6PD polymorphisms and hemoglobin (Hb) phenotypes in children in Lagos, Nigeria. Seventy-eight children [55 with Hb AA (β^Α/β^A) and 23 with Hb AS (β^Α/β^S) trait] and 65 Hb SS (β^S/β^S) (HBB: c.20A>T) subjects in steady state with age range between 5–15 years were recruited for the study. Hemoglobin phenotypes of all study participants were carried out using alkaline electrophoresis and solubility tests. Genomic DNA was extracted from whole blood and restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) was used to determine the G202A and the A376G mutations of the G6PD gene. The genotype and allele distributions of G6PD G202A and A376G according to the Hb phenotypes were not statistically significant (p?>?0.05). The minor allele frequency 202A was 0.15 (15.0%) and 0.14 (14.0%) in cases and controls, respectively. The overall frequency of 376G allele in the case group was 0.35 (35.0%) and 0.38 (38.0%) in the control group. No statistical significance was observed in the genotype and allele distributions of A376G in both the case and control groups (p?>?0.05). The G6PD A? frequency in Hb SS subjects and the control group were 6.2 and 2.6%, respectively. G6PD G202A and A376G polymorphisms were not associated with Hb phenotypes and the allele distributions of 202A and 376G in this study are typical of West African populations.     

Molecular Epidemiological Survey of Glucose-6-Phosphate Dehydrogenase Deficiency and Thalassemia in Uygur and Kazak Ethnic Groups in Xinjiang,Northwest China

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and thalassemia occur frequently in tropical and subtropical regions, while the prevalence of relationship between the two diseases in Xinjiang has not been reported. We aimed to determine the prevalence of these diseases and clarify the relationship between genotypes and phenotypes of the two diseases in the Uygur and Kazak ethnic groups in Xinjiang. We measured G6PD activity by G6PD:6PGD (glucose acid-6-phosphate dehydrogenase) ratio, identified the gene variants of G6PD and α- and β-globin genes by polymerase chain reaction (PCR)-DNA sequencing and gap-PCR and compared these variants in different ethnic groups in Xinjiang with those adjacent to it. Of the 149 subjects with molecular analysis of G6PD deficiency conducted, a higher prevalence of the combined mutations c.1311C?>?T/IVSXI?+?93T?>?C and IVSXI?+?93T?>?C, both with normal enzymatic activities, were observed in the Uygur and Kazak subjects. A case of rare mutation HBB: c.135delC [codon 44 (?C) in the heterozygous state], a heterozygous case of HBB: c.68A?>?G [Hb G-Taipei or β22(B4)Glu→Gly] and several common single nucleotide polymorphisms (SNPs) were found on the β-globin gene. In conclusion, G6PD deficiency with pathogenic mutations and three common α-thalassemia (α-thal) [–?–^SEA, ?α^3.7 (rightward), ?α^4.2 (leftward)] deletions and point mutations of the α-globin gene were not detected in the present study. The average incidence of β-thalassemia (β-thal) in Uygurs was 1.45% (2/138) in Xinjiang. The polymorphisms of G6PD and β-globin genes might be useful genetic markers to trace the origin and migration of the Uygur and Kazak in Xinjiang.     

Erythrocyte Superoxide Dismutase,Catalase and Glutathione Peroxidase in Glucose-6-Phosphate Dehydrogenase Deficiency

Glucose-6-phosphate dehydrogenase (G-6-PD) deficient erythrocytes are particularly sensitive to oxidant stress. In order to evaluate if these cells are protected against oxidant damage, we assayed the antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-Px) in erythrocytes of G-6-PD deficient (hemizygous and heterozygous) subjects. Normal levels of antioxidant enzymes were found in all subjects examined both with positive and negative histories of haemolytic crisis after fava bean or drug ingestion. In contrast, high levels of catalase and GSH-Px were found in a small group of G-6-PD deficient subjects (hemizygous and heterozygous) with β-thalassaemia trait, probably by reason of the chronically enhanced oxidant stress which is present in β-thalassaemia.     

Genetic Background of the Sickle Cell Disease Pediatric Population of Dakar,Senegal, and Characterization of a Novel Frameshift β-Thalassemia Mutation [HBB: c.265_266del; p.Leu89Glufs*2]

Sickle cell disease is a genetic disorder with a large variability in the pattern and severity of clinical manifestations. Different genetic modulators have been identified but very few epidemiologic data are available on these modifier genes in Senegal. This study aimed to determine their prevalence in a Senegalese sickle cell disease pediatric population. The following genetic parameters were genotyped in 295 sickle cell disease children of the Dakar pediatric hospital: sickle cell disease genotype [β^S/β^S (HBB: c.20A>T), β^S/β^C (HBB: c.19G>A), β^S/β⁰-thalassemia (β⁰-thal)], XmnI polymorphism, the five most common α-thalassemia (α-thal) deletions and the A(–) and Betica glucose-6-phosphate-dehydrogenase (G6PD) deficient variants. Despite very few β^S/β^C and β^S/β⁰-thal children (1.0% each), a novel frameshift β⁰-thal mutation was characterized: HBB: c.265_266del; p.Leu89Glufs*2. The –α^3.7 (rightward) deletion was the only α-thal deletion identified in this cohort (12.0% allelic frequency). Most of β^S/β^S patients (61.9%) were homozygous for the XmnI polymorphism and assumed to carry a Senegal/Senegal β^S haplotype. The remaining haplotypes were predominantly of the Benin type. While the Betica G6PD variant was quite frequent (13.0%), a low frequency of the A(–) variant was detected (1.0–2.0%). The systematic genotyping of the –α^3.7 deletion and of the G6PD Betica variant in sickle cell disease patients from Senegal could be useful to identify patients at risk for several complications, such as cerebral vasculopathy, where it has been demonstrated that a normal α-globin genotype and G6PD deficiency are predisposing factors. These patients should be eligible for a transcranial Doppler examination that is not routinely offered in Senegal.     

The Molecular Analysis of β-Thalassemia Mutations in Lorestan Province,Iran

β-Thalassemia (thal) is one of the most common genetic disorders in Iran and other countries. Getting information on the distribution of mutations in different ethnic groups of Iran is of fundamental importance for the purpose of health planning and prenatal diagnosis programs. One hundred and thirty chromosomes from 65 unrelated homozygous β-thal patients were investigated for β‐globin gene mutations by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). The most common mutations of the Mediterranean region were examined in this study. Our results showed that the frameshift codons (FSC) 36/37 (–T) mutation, with a frequency of 33.8%, is the most common mutation in Lorestan Province. The other most frequent mutations were of the Mediterranean type and consisted of IVS-II-1 (G?→A), IVS-I-110 (G?→A), FSC 8/9 (+G) and IVS-I-5 (G?→C) with frequencies of 27.7, 11.5, 10.8 and 4.5%, respectively. The less frequent alleles, IVS-II-745 (C?→G), FSC 5 (–CT), IVS-I (25 bp deletion) and FSC 44 (–C) accounted for only 3.9% of the mutations. The unknown alleles comprised 7.7% of the mutations. These data showed that the spectrum of mutations found in Lorestan Province was different from those reported from other thalassemic regions of Iran and also of some neighboring countries.     

The Spectrum of β-Thalassemia Mutations in Kermanshah Province in West Iran and its Association with Hematological Parameters

β-Thalassemia (β-thal) is a hereditary autosomal disorder with decreased or absent β-globin chain synthesis. Two hundred and one unrelated β-thal carriers, attending the Kermanshah Medical Genetics Laboratory, Kermanshah, Iran, were investigated for β-globin gene mutations by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and direct sequencing. Eighteen different mutations were identified in these subjects. Four of the mutations accounted for about 75.0% of the studied cases. IVS-II-1 (G>A) was the most frequent (45.8%) followed by codons 8/9 (+G) (15.9%), IVS-I-110 (G>A) (8.0%), IVS-I-6 (T>C) (5.5%), IVS-I-1 (G>A) (3.5%) and codon 44 (–C) (3.5%); the remaining 12 mutations were present with a frequency less than 3.0%. The mean corpuscular volume (MCV) values for males and females were 63.7 ± 3.7 and 63.2 ± 3.2 fL, respectively, while these values were 19.3 ± 1.6 and 19.3 ± 1.4 pg for mean corpuscular hemoglobin (Hb) (MCH). The mean Hb A₂ values for males and females were 4.4 ± 0.5 and 4.1 ± 0.6%, respectively. This study provides a distribution guide for β-thal mutations in Kermanshah Province, West Iran.     

Mutation Spectrum of β-Thalassemia and Other Hemoglobinopathies in Chittagong,Southeast Bangladesh

Abstract

Thalassemia is one of the most common autosomal recessive blood disorders in the world. It shows a variety of clinical expression, starting from asymptomatic to severe blood transfusion dependence. More than 500 alleles have been characterized in or around the β-globin region. Moreover, most geographical regions have their own characteristics, frequency and availability of these alleles, predominantly circulating within the communities present in that particular region. In this study, we explored the spectrum of β-thalassemia (β-thal) alleles present in Chittagong, Southeast Bangladesh. This study comprises β-thal and Hb E (HBB: c.79?G?>?A) patients from in and around the area of Chittagong. Not only exploring the complete β-globin mutation spectrum of the area, but we also tried to look at the origin of the mutated alleles. The β-thal mutations of Bangladesh show a relatively wide spectrum of alleles, which further demonstrates the heterogeneity of the disease in this country. Although our study showed that the majority of the mutations have their origin in neighboring countries such as India, countries of Southeast Asia, Pakistan, etc., some unusual alleles do not originate in neighboring countries and put a little more diversity in the overall spectrum of β-thal-specific alleles. Overall, this study demonstrates the mutation spectrum related to β-thal in Chittagong, Southeast Bangladesh.     

Prevalence of Thalassemia Traits and Iron Deficiency Anemia in Sindh,Pakistan

Among microcytic hypochromic anemias, the most common disorders are iron deficiency anemia and co-pathological conditions such as α- or β-thalassemia (α- or β-thal) traits. The aim of the present study was to determine the frequency and prevalence of iron deficiency anemia and α- or β-thal traits based on clinical laboratory data across different ethnic groups in five districts of Sindh Province, Pakistan. The present retrospective study analyzed 3 years (2012–2015) of encoded and unlinked clinical laboratory data, and identified 3030 microcytic hypochromic anemia cases. The data contained complete blood counts (CBCs) with smear morphology examinations, serum ferritin levels, and hemoglobin (Hb) electrophoreses. After reviewing the data, 994 confirmed subjects (iron deficiency anemia and α- and β-thal traits) were then selected for the present study. The prevalence of α- and β-thal traits was highest in Badin district (35.27%), while the prevalence of iron deficiency anemia was highest in Larkana district (30.73%). According to the ethnic-wise distribution, higher numbers of α- and β-thal trait cases were seen in the Sindhi ethnic group [375 (64.21%) and 283 (69.02%), respectively] than in the other ethnic groups. In addition, a higher distribution of β-thal trait cases was observed in the Sindhi ethnic group [n?=?327 (56%)] in α- and β-thal cases overall. Findings from the present study strongly suggested that screening is important not only for β-thal trait but also other traits as well. However, careful monitoring of CBC parameters, including red blood cell (RBC) indices and morphology, along with clinical findings are essential to diagnose carrier cases, especially in high prevalence areas.     

Mutational Spectrum of Thalassemias and other Hemoglobinopathies in West Bengal,Eastern India

Thalassemia, an autosomal recessive blood disease, shows a variety of clinical expression in terms of asymptomatic to severe blood transfusion dependence. More than 500 alleles have been characterized in or around the β-globin region. Most of the geographical regions have their own characteristic alleles that predominantly circulate within the communities present in that particular region. In this article, we try to throw some light to explore the spectrum of β-thalassemia (β-thal) alleles present in West Bengal, the eastern part of India. This study comprises thalassemia carriers and diseased persons from different districts of West Bengal. We not only explored the complete mutational spectrum of this state but we also tried to fix the critical range of the values of different hematological parameters [Hb A₂, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH)] for the heterozygotes or carriers of β-thal with the same mutational background. At the same time, we also tried to evaluate the maximum weighted frequency of these parameters for the heterozygotes or carriers of β-thal with the same mutational background, so that by observing these cut-off values of standard hematological parameters, we were able to predict the carrier or diseased status for mass scale screening and also try to correlate the values of these parameters with different combinations of β-thal mutation-specific alleles that can be more informative in mass scale (carrier) screening.     

Hb Koya Dora [α142, Term→Ser (TAA>TCA in α2)]: A Rare Mutation of the α2 Gene Stop Codon Associated with α-Thalassemia

Hb Constant Spring [(Hb CS) α142, Term→Gln (TAA>CAA in α2)] and Hb Koya Dora [α142, Term→Ser (TAA>TCA in α2)] both involve mutations of the α2 gene stop codon and while Hb CS is the most frequent cause of nondeletional α-thalassemia (α-thal) in Southeast Asia, Hb Koya Dora is limited to a restricted population from Andhra Pradesh, India. Here we identify a homozygous case of Hb Koya Dora and confirm the structure of the 31 residue α chain extension.     

Development and evaluation of a reverse dot blot assay for the simultaneous detection of six common Chinese G6PD mutations and one polymorphism

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common inherited disorder worldwide including southern China. We developed and validated a reverse dot blot (RDB) assay for the rapid and simultaneous genotyping of six mutations (c.95A>G, c.871G>A, c.1004C>T, c.1024C>T, c.1376G>T and c.1388G>A), that were common mutations in the Chinese G6PD deficiency population, and one polymorphism (c.1311C>T). Reliable genotyping of wild-type and mutant genomic DNA samples was achieved by means of a test strip onto which allele-specific oligonucleotide probe lines are fixed in parallel. This method involves a multiplex PCR amplification of three fragments in the G6PD target sequence and a manual hybridization/detection protocol. The entire procedure starting from blood sampling to the identification of mutations requires less than 6 h. The diagnostic reliability of this reverse dot blot assay was evaluated on 207 pre-typed samples by using direct DNA sequence analysis in a blind study. The reverse dot blot typing was in complete concordance with the reference method. The reverse dot blot assay was proved to be a simple, rapid, highly accurate, and cost-effective method to identify common G6PD mutations in Chinese population.     

Prevalence of α+-Thalassemia in the Scheduled Tribe and Scheduled Caste Populations of Damoh District in Madhya Pradesh,Central India

This study was carried out to ascertain the allelic frequency of α⁺-thalassemia (α⁺-thal) in Scheduled caste and scheduled tribe populations of the Damoh district of Madhya Pradesh, India. Random blood samples of Scheduled tribe (267) and Scheduled caste (168), considering the family as a sampling unit, were analyzed for the presence of the –α^3.7 (rightward) (NG_000006.1: g.34164_37967del3804) and –α^4.2 (leftward) (AF221717) deletions. α⁺-Thal was significantly higher in the Scheduled tribals (77.9%) as compared to the scheduled caste population (9.0%). About 58.0% scheduled tribals carried at least one chromosome with the –α^3.7 deletion and 20.0% scheduled tribals carried the –α^4.2 deletion. Frequency for the –α^3.7 allele was 0.487 in the scheduled tribal populations in comparison to 0.021 in scheduled castes. Allelic frequency for –α^4.2 was 0.103 and 0.024, respectively, in the above communities. No Hardy-Weinberg equilibrium for α-thal gene (p?相似文献   

β-Thalassemia Intermedia Caused by Compound Heterozygosity for Hb Lepore-Hollandia and β-Thalassemia is Rare in the Indian Population

Abstract

Compound heterozygosity for one of the Hb Lepore mutations and β-thalassemia (β-thal) is a rare cause of non transfusion-dependent thalassemia. We report a 4-year-old boy who presented clinically as homozygous/compound heterozygous β-thal intermedia (β-TI), an impression that was corroborated by the initial hemoglobin (Hb) high performance liquid chromatography (HPLC). However, the correct diagnosis of a rare compound heterozygous Hb Lepore-Hollandia/β-thal was revealed after parental studies and molecular analyses including β-globin gene sequencing. Our patient highlights the importance of a logical stepwise multi modality approach and the vital importance of parental screening and molecular studies in accurate characterization of complex hemoglobinopathies. Correct diagnosis is especially crucial if pre natal detection is anticipated for future pregnancies. Molecular analyses alone may not compensate for the unavailability of parental testing. This is because the molecular results may be misinterpreted, especially if limited tests are conducted. The infrequent prior reports of this combination from distant parts of the Indian subcontinent suggests that the origin of Hb Lepore-Hollandia from sporadic mutations occurs in isolated families.     

NBT纸片定性法与G6PD/6PGD比值法在大样本G6PD缺陷症筛查中的联合应用

目的：探讨联合应用葡萄糖-6-磷酸脱氢酶（G6PD）四氮唑蓝（NBT）纸片定性法与G6PD／6PGD比值定量法在大样本筛查中的可行性。方法：用NBT纸片定性法对501例贵州省江口县土家族、525例从江县侗族、586例荔波县瑶族共1612例成人进行定性初筛，再用G6PD／6PGD比值法对初筛阳性样本定量复查。结果：NBT纸片定性法共初筛出G6PD缺陷患者129例，G6PD／G6PD比值法确诊G6PD缺陷123例，2种方法的符合率高达95．35％。结论：对大样本G6PD缺陷症的筛查，先用NBT纸片定性法进行初筛，再用G6PD／6PGD比值法复查确诊，2法联合应用可以提高G6PD缺陷症检出率和节约大量经费和时间。     

Molecular heterogeneity of G6PD deficiency in an Amazonian population and description of four new variants

To characterize the molecular variation in the glucose-6-phosphate dehydrogenase gene (G6PD), 196 asymptomatic and unrelated male G6PD-deficient blood donors from Belém, an Amazonian metropolis (Brazil), were analyzed. This deficiency was detected by horizontal agarose gel electrophoresis and quantitative spectrophotometric assay for enzyme activity. The mutations were searched by PCR/RFLP, SSCP, and direct DNA sequencing. The most frequent G6PD variant was the widespread and common G6PD A- (202G --> A, 376A --> G) observed in 161 subjects (82.1%). Besides this, we found another form of G6PD A- (968T --> C, 376A --> G) in 14 (7.1%) individuals, G6PD Seattle (844G --> C) in 4.6%, G6PD Santamaria (542A --> T, 376A --> G) in 2.5%, and G6PD Tokyo (1246G --> A) in one blood donor. Four novel variants were also identified: G6PD Belém (409C --> T; Pro137His), G6PD Ananindeua (376A --> G, 871G --> A; Asn126Asp, Val291Met), G6PD Crispim with four point mutations (375G --> T, 379G --> T, 383T --> C, and 384C --> T) leading to three amino acid substitutions (Met125Ile, Ala127Ser, and Leu128Pro), and G6PD Amazonia (185C --> A; Pro62His). The reported frequencies do not reflect the real values for blood donors from Belém, since an excess of individuals with "non A-" phenotype was included in this study to enhance the probability to find rare variants. Haplotype analyses were carried out for the less common G6PD variants identified in our study using PCR/RFLP for five polymorphic sites (FokI, PvuII, PstI, BclI, NlaIII). G6PD Crispim and G6PD Amazonia variants presented the most common haplotype found in G6PD B (- - + - -). G6PD Belém presented two haplotypes (- - + + +, - + + + +) and G6PD Ananindeua was found with the + - + - + haplotype. The reported heterogeneity probably is due to the great miscegenation, characteristic of the population of the Amazonian region, besides the apparently common occurrence of recurrent mutations in the G6PD gene.     

Hb Iberia [α104(G11)Cys → Arg,TGC>CGC (α2) (HBA2:c.313T>C)], a New α-Thalassemic Hemoglobin Variant Found in the Iberian Peninsula: Report of Six Cases

We report a new structural defect of the α2-globin chain presenting with moderate microcytic hypochromic anemia, in six individuals from three unrelated families, living in Portugal and Spain. α-Globin gene deletions were ruled out by gap-polymerase chain reaction (gap-PCR) and multiplex ligation-dependent probe amplification (MLPA). Direct sequencing of the α2-globin gene revealed a substitution of codon 104 [α104(G11)Cys→Arg, TGC>CGC (α2) (HBA2:c.313T>C)]. This new variant, not detectable by high performance liquid chromatography (HPLC) or electrophoresis, was called Hb Iberia, as it was observed for the first time in families from the Iberian Peninsula.

Although the mutant allele is transcribed, as indicated by the balanced mRNA α/β ratio, the abnormal α2 chain could not form a stable tetramer as the cysteine and arginine residues, located at the α1β1 contact, differ in size, charge and hydrophobicity.

Hb Iberia is the third mutation described at codon 104 on the α-globin genes, namely, Hb Sallanches (α2, TGC>TAC) and Hb Oegstgeest (α1, TGC>AGC), also characterized as unstable hemoglobins (Hbs), present on an α-thalassemic phenotype.     

Molecular heterogeneity of glucose-6-phosphate dehydrogenase deficiency in Malays in Malaysia

Multiplex polymerase chain reaction (PCR) using multiple tandem forward primers and a common reverse primer (MPTP) was recently established as a comprehensive screening method for mutations in X-linked recessive diseases. In the work reported here, MPTP was used to scan for mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene. Mutations in exons 3,4,5,6,7,9, 11, and 12 of the G6PD gene were screened by MPTP in 93 unrelated Malaysian patients with G6PD deficiency. Of the 93 patients, 80 (86%) had identified mutations. Although all of these were missense mutations, identified nucleotide changes were heterogeneous, with 9 mutations involving various parts of the exons. These 9 mutations were G-to-A nucleotide changes at nucleotide 871 of the G6PD gene (G871A), corresponding to G6PD Viangchan, G6PD Mediterranean (C563T), G6PD Vanua Lava (T383C), G6PD Coimbra (C592T), G6PD Kaiping (G1388A), G6PD Orissa (C131G), G6PD Mahidol (G487A), G6PD Canton (G1376T), and G6PD Chatham (G1003A). Our results document heterogeneous mutations of the G6PD gene in the Malaysian population.     

A Rare Association of α0-Thalassemia (– –SEA) and an Initiation Codon Mutation (ATG→A-G) of the α2 Gene Causes Hb H Disease in Thailand

Several rare and hitherto unidentified non deletional α-thalassemias (α^Tα or αα^T) have been reported from Thailand within the past few years. Interactions of these determinants with α⁰-thalassemia (thal) (– –/), which is highly prevalent in this region, give rise to various genotypes (– –/α^Tα or – –/αα^T) underlying Hb H disease. We report herein the interaction of a rare initiation codon mutation of the α2 gene and α⁰-thal in a Thai boy with Hb H disease. This finding highlights a wide variety of molecular pathology of the α-globin genes underlying α-thal syndrome in Southeast Asia.