Hemoglobinopathy: molecular epidemiological characteristics and health effects on Hakka people in the Meizhou region, southern China

Global distribution of β-thalassemia mutations: An update

One excellent illustration of how a single gene abnormality may result in a spectrum of disease incidence is the incredible phenotypic variety of β-thalassemia, which spans from severe anemia and transfusion needs to an utterly asymptomatic sickness. However, genetic causes of β-thalassemia and how the anemia's severity might be altered at various stages in its pathophysiology have been well investigated. There are currently known to be more than 350 mutations that cause genetic disease. However only 20 β thalassemia mutations account for more than 80% of the β thalassemia mutation across the globe due to phenomenon of geographical clustering where each population has a few common mutations together with a varying number of rare ones. Due to migration of the population, the spectrum of thalassemia mutation in changing from time to time. In this review, efforts are made to collate β globin gene mutations in different countries and populations.

The Need for Translational Epidemiology in Beta Thalassemia Syndromes: A Thalassemia International Federation Perspective

Epidemiology is the practical tool to provide information on which policy makers should base planning of services. Epidemiological data for thalassemia is based on inaccurate and often conflicting measurements. This study attempts to demonstrate with examples the sources of inaccuracy and confusion. The Thalassemia International Foundation (TIF) suggests that congenital disorders, for which increasing complications and premature death are avoidable through appropriate treatment and follow-up, should be given priority based on accurate data and patient registries. Moreover, only accurate information about this issue, especially for developing countries, will move national health resources in the right direction.

The gene spectrum of thalassemia in Yangjiang of western Guangdong Province

Background: Thalassemia presents a higher incidence in southern China. The objective of this study is to analyze the genotype distribution of thalassemia in Yangjiang, a western city of Guangdong Province in China. Methods: The genotypes of suspected cases with thalassemia were tested by PCR and reverse dot blot (RDB). Unidentified rare thalassemia genotypes of the samples were further ascertained by PCR and direct DNA sequencing. Results: Among 22467 suspected cases with thalassemia, 7658 cases were found with thalassemia genotypes using our PCR-RDB kit. Among these 7658 cases, 5313 cases were found with α-thalassemia (α-thal) alone, --^SEA/αα was the most common genotype, accounting for 61.75% of α-thal genotypes, and the following mutations were found: α^3.7/αα, -α^4.2/αα, α^CSα/αα, α^WSα/αα, and α^QSα/αα. A total of 2032 cases were found with β-thalassemia (β-thal) alone. β^CD41-42/β^N, β^IVS-II-654/β^N, and β^-28/β^N accounted for 80.9% of all β-thal genotypes, and the following genotypes were found: β^CD17/β^N, β^CD71-72/β^N, and β^E/β^N. Compound heterozygotes of β-thal and β-thalassemia homozygotes were identified in 11 and five cases, respectively, in this study. α-thal combined with β-thal was identified in 313 cases, showing 57 genotype combinations of the coincidence of both Hb disorders; one extreme patient had a genotype of --^SEA/α^WSα and β^CD41-42/β^-28. In addition, four rare α-mutations (--^THAI, HKαα, Hb Q-Thailand, and CD31 AGG>AAG) and six rare β-mutations (CD39 CAG>TAG, IVS-Ⅱ-2 (-T), -90(C>T), Chinese ^Gγ⁺(Aγδβ)0, CD104 (-G), and CD19 A>G) were also found in this study population. Conclusion: This study provided detailed genotypes of thalassemia in Yangjiang of western Guangdong Province in China and reflected the complexity of genotypes in this high-prevalence region, and this would be valuable for diagnosis and counseling for thalassemia in this area.

Clinical validation of a single-tube PCR and reverse dot blot assay for detection of common α-thalassaemia and β-thalassaemia in Chinese

Objective

To evaluate a novel reverse dot blot assay for the simultaneous detection six types of common α-thalassaemia alleles (three deletional and three common non-deletional mutations) and 19 types of common β-thalassaemia alleles in a Chinese population.

Methods

Genomic DNA samples were collected from three hospitals in southern China. The novel thalassaemia gene assay involved one multiplex polymerase chain reaction amplification system and one round of hybridization. Each of the clinically validated DNA samples was re-tested using the new multiplex polymerase chain reaction/reverse dot blot assay II (M-PCR/RDB II) assay in a double-blind manner.

Results

A total of 1060 unrelated study participants, including 829 patients with thalassaemia and 231 healthy control subjects, were analysed. The whole PCR and RDB procedures were completed in 260 min. All the samples, including heterozygous thalassaemia, homozygous thalassaemia and compound heterozygous thalassaemia, were correctly genotyped, yielding 100% concordance with the reference assays. HKαα/--^SEA and HKαα/−α^4.2, which were not included in the detection panel, yielded a contradictory result with this new assay.

Conclusion

The novel M-PCR/RDB II assay was simple, rapid and accurate, suggesting that it could be used for the genetic screening and clinical diagnosis of common α-thalassaemia and β-thalassaemia variants in Chinese populations.

Human serum albumin variants in China: a molecular epidemiological investigation and literature review

Background

Bisalbuminemia is a hereditary and/or acquired abnormality characterized by a double albumin (ALB) band on serum protein electrophoresis. However, there have been no epidemiological investigations of ALB variants in Chinese populations.

Methods

This retrospective study examined 71,963 unrelated subjects from five provinces in southern China. ALB variants were screened by cellulose acetate electrophoresis at pH 8.6 and ALB mutations were confirmed by polymerase chain reaction-DNA sequencing.

Results

The average incidence of inherited bisalbuminemia in the southern Chinese population was 0.0264% (19/71,963). Thirteen cases showed slow and six showed fast genetic variants on cellulose acetate electrophoresis. Four kinds of ALB variants were identified: proalbumin Lille (p.Arg23His), ALB Castel di Sangro (p.Lys560Glu), ALB Fukuoka-1 (p.Asp587Asn), and a novel ALB Wuxi (p.Lys562Glu). The gene frequency of ALB variants in the Wuxi region (0.126%, 13/10,297) was significantly higher than in other regions in southern China, and 90.9% (10/11) of cases of proalbumin Lille were also found in the Wuxi region.

Conclusions

This study provides the first report of the detailed prevalence and molecular characterization of ALB variants in southern China. Compared with other areas of China, Wuxi had a different pattern of ALB variants and a high prevalence of proalbumin Lille.

Molecular analysis of alpha- and beta-thalassemia in Meizhou region and comparison of gene mutation spectrum with different regions of southern China

BACKGROUND

Thalassemia is a group of inherited autosomal recessive hemolytic anemia disease caused by reduced or absent synthesis of globin chain/chains of hemoglobin. Only few studies showed the molecular characterization of α- and β-thalassemia in Meizhou city of China.

METHODS

A total of 22,401 individuals were collected; hematological and hemoglobin electrophoresis analysis and thalassemia genetic testing were performed.

RESULTS

Eleven thousand and thirty (49.24%) cases with microcytosis (mean corpuscular volume (MCV) < 82 fl), 11,074 (49.44%) cases with hypochromia (mean corpuscular Hb (MCH) < 27 pg) in 22,401 subjects, 11,085 cases with abnormal hemoglobin results were identified in subjects aged ≥6 months. 7,322 (32.69%) subjects harbored thalassemia mutations, including 4,841 (21.61%) subjects with α-thalassemia, 2,237 (9.99%) with β-thalassemia, and 244 (1.09%) with α-thalassemia combined β-thalassemia. 18 genotypes of α-thalassemia mutations and 27 genotypes of β-thalassemia mutations were characterized. The most frequent α gene mutation was --SEA (64.69%), followed by -α3.7 (19.93%), -α4.2 (7.73%), αCS α (3.97%), and αWS α (2.83%). The six most common β-thalassemia mutations were IVS-II-654 (C>T) (39.79%), CD41-42 (-TCTT) (33.02%), -28 (A>G) (10.38%), CD17 (A>T) (9.08%), CD27-28 (+C) (2.14%), and CD26 (G>A) (2.02%). In addition, MCV and MCH were sensitive markers for α- and β-thalassemia except for -α3.7 /αα, -α4.2 /αα, αCS α/αα, αWS α/αα, and βCap+40-43 /βN .

CONCLUSIONS

The --SEA , -α3.7 , and -α4.2 deletions were the main mutations of α-thalassemia, while IVS-II-654 (C>T), CD41-42 (-TCTT), -28 (A>G), and CD17 (A>T) mutations of β-thalassemia in Meizhou. There were some differences in thalassemia mutation frequencies in Meizhou city from other populations in China.

Molecular characterization of hemoglobinopathies and thalassemias in Northern Guangdong Province, China

ABSTRACT

To detect the molecular characterization of hemoglobinopathies and thalassemias in Northern Guangdong Province of China.We recruited 10,285 subjects who were screened for hemoglobin (Hb) variants and thalassaemia genotypes in the outpatient department of Yuebei People's Hospital from January 2018 to December 2020. The subjects collected venous blood samples for blood cell parameter analysis and Hb electrophoresis analysis. When the average red blood cell volume is <82 fL, or the average red blood cell Hb is <27 pg, or HbA2 > 3.5%, or HbA2 < 2.5%, or HbF > 2.0%, the screening is positive if one of them is satisfied. All subjects who were screened positive were tested for the thalassaemia gene by gap-polymerase chain reaction, PCR-based reverse dot blot, and DNA sequencing.Among all subjects screened, the overall prevalence of hemoglobinopathies and thalassemias were 0.46% (47/10,285) and 21.02% (2162/10,285) in Northern Guangdong Province. We found that Hb Q-Thailand is the most common, and other types of hemoglobinopathies are followed by Hb E, Hb New York, Hb G-Chinese, Hb G-Coushatta, Hb J-Bangkok, Hb J-Broussais, Hb Ottawa, and Hb G-Taipei. We identified 1340 cases (13.03%) of α-thalassemia, mainly includes --SEA deletion (71.64%), -α3.7 deletion (12.01%), -α4.2 deletion (4.78%). And identified 652 cases (6.34%) of β-thalassemia, the most prevalent being CD 41/42(-TTCT) (35.89%), IVS-II-654 (C > T) (33.44%), CD 17 (A > T) (10.28%) and -28(A > G) (9.66%). Furthermore, there are 170 cases (1.65%) of α combined β thalassaemia. In addition, we found a rare case with -80 (T > A) of β-thalassemia. The results of this study found a high prevalence of hemoglobinopathies and thalassemias in Northern Guangdong Province, China. There were some differences molecular characterizations of thalassemia in different areas of China.Our results enriched the related information of hemoglobinopathies and thalassemias in the region, which provided valuable references for the prevention and control of thalassemia.

Cell count-based parameters and algorithms for thalassaemia trait screening in the southern Chinese population

INTRODUCTION

Thalassaemia trait (TT) is potential to be missed clinically, especially normocytic thalassaemia. We aimed to establish discriminant functions (DFs) and an algorithm for detecting microcytic or normocytic TT in epidemiological screening.

METHODS

The receiver operating characteristics (ROC) curve analysis was used to determine the diagnostic performance of the proposed formulas in differentiating TT and nonthalassaemia (non-TT). DFs combined the two blood count parameters with the highest performance, based on the area under the curve (AUC) value, into mathematical formulas, using logistic regression. The diagnostic efficacy of DFs was subsequently evaluated in 761 participants, and reliability (including adjusted agreement [AA] and Kappa values) and validity (including sensitivity, specificity, likelihood ratio and Youden's Index) were calculated.

RESULTS

Among microcytic participants, the proposed DFs showed good diagnostic performance (in females: AUC = 0.892 [DF1 = 0.015 × RDW-CV/RBC - 0.096 × RDW-SD/RBC + 1.29], in males: AUC = 0.861 [DF2=-0.025 × RDW-SD/RBC - 0.035 × MCV/RBC + 1.415]). Youden's Index, AA and Kappa values for microcytic TT detection were 0.72, 0.86, and 0.72 and 0.63, 0.81 and 0.63 for females and males, respectively. In normocytic participants with RDW-CV/RBC ≤ 3.54, DF3=-0.38 × MCH-0.02 × MCHC+17.37 achieved AUC = 0.857 in females, whereas DF4 = 0.007 × MCV-0.113 × MCH+2.829 achieved AUC = 0.969 in males. The Youden's Index, AA and Kappa values for the proposed DFs for thalassaemia detection were 0.69, 0.84 and 0.67 in females, 0.76, 0.91 and 0.71 in males, respectively.

CONCLUSION

The proposed DFs performed well in the detection of TT among participants with microcytic and normocytic parameters and could be utilized in epidemiological study for TT.

Molecular epidemiology and hematologic characterization of δβ-thalassemia and hereditary persistence of fetal hemoglobin in 125,661 families of greater Guangzhou area, the metropolis of southern China

Background

Individuals with δβ-thalassemia/HPFH and β-thalassemia usually present with intermedia or thalassemia major. No large-scale survey on HPFH/δβ-thalassemia in southern China has been reported to date. The purpose of this study was to examine the molecular epidemiology and hematologic characteristics of these disorders in Guangzhou, the largest city in Southern China, to offer advice for thalassemia screening programs and genetic counseling.

Methods

A total of 125,661 couples participated in pregestational thalassemia screening. 654 subjects with fetal hemoglobin (HbF) level ≥ 5% were selected for further investigation. Gap-PCR combined with Multiplex ligation dependent probe amplification (MLPA) was used to screen for β-globin gene cluster deletions. Gene sequencing for the promoter region of HBG1 /HBG2 gene was performed for all those subjects.

Results

A total of 654 individuals had hemoglobin (HbF) levels≥5, and 0.12% of the couples were found to be heterozygous for HPFH/δβ-thalassemia, including Chinese ^Gγ (^Aγδβ)⁰-thal, Southeast Asia HPFH (SEA-HPFH), Taiwanese deletion and Hb Lepore–Boston–Washington. The highest prevalence was observed in the Huadu district and the lowest in the Nansha district. Three cases were identified as carrying β-globin gene cluster deletions, which had not been previously reported. Two at-risk couples (0.0015%) were required to receive prenatal diagnosis. We also found 55cases of nondeletional-HPFH (nd-HPFH), including 54 with Italian nd-HPFH and one with the ^Aγ-197C-T heterozygous state. It is difficult to discriminate between Chinese ^Gγ (^Aγδβ)⁰-thal and Italian nd-HPFH carriers using hemoglobin (Hb) analysis.

Conclusions

This study is the first to describe the familial prevalence of HPFH/δβ-thalassemia and the high-risk rate in Greater Guangzhou Area, and the findings will support the implementation of thalassemia screening for three common deletions by gap-PCR. We also presented a systematic description of genotype-phenotype relationships which will be useful for genetic counseling and prenatal diagnostic services for β-thalassemia intermedia.

A Pitfall in HbA1c Testing Caused by Hb Long Island Hemoglobin Variant

BACKGROUND

Although many factors may interfere with hemoglobin (Hb)A1c measurement, Hb variants are among the most important factors.

METHODS

We tested the HbA1c levels of the patient, a 32 year old Manchu Chinese woman, during a routine health check. We used different methods, including high-performance liquid chromatography (HPLC) and capillary electrophoresis, to test specimens from the patient. Next, we tested the specimen further using polymerase chain reaction (PCR) and sequencing.

RESULTS

We discovered that our patient, who had an HbA1c value of 0, also has an Hb variant, Hb Long Island, which we found during the HbA1c analysis as part of her routine health check at the Health Management Center in the General Hospital of Tianjin Medical University, Tianjin, China. Also, we discovered that the exon 1 of β gene contained transversion mutations, with 1 heterozygous and 1 homozygous variant (HBB:c.8A > C, 9T > C). These gene mutations resulted in an amino-acid change (His to Pro) and a decrease in HbA1c value.

CONCLUSIONS

When there is no correlation between the clinical signs, glycemic status, and glycated Hb levels of the patient, the chromatogram of HbA1c should be carefully checked to detect possible variants that cause interference in the measurement.

Genetic investigation of haemoglobinopathies in a large cohort of asymptomatic individuals reveals a higher carrier rate for β-thalassaemia in Sichuan Province (Southwestern China)

The incidence of haemoglobinopathy is high in China, especially south of the Yangtze River. However, the exact status of haemoglobinopathy in Sichuan is unknown. To carry out a detailed research of haemoglobinopathy in individuals living in Sichuan, 13,298 subjects without clinical symptoms who were living in Sichuan Province, with an age distribution of 5–73 years, were included in this study. Between March 2014 and July 2017, these subjects received examinations at the Medical Lab of Chengdu Women's & Children's Central Hospital. Mean corpuscular volume (MCV) < 82 fL or mean corpuscular haemoglobin (MCH) < 27 pg was used to indicate haemoglobinopathy carriers. Abnormal haemoglobin was screened by electrophoresis, and genes were sequenced to identify genotypes. Genotype diagnosis of alpha- and beta-thalassaemia was carried out by using PCR and shunt hybridization. There were 638 suspected haemoglobinopathy carriers (4.80%, 638/13,298). DNA sequencing identified 6 subjects with abnormal haemoglobin genotypes and 15 subjects with Hb E. The frequency of heterozygosity for thalassaemia was 4.12% (1.48% for α-thalassaemia and 2.61% for β-thalassaemia) in Sichuan Province. The mutation spectrum of α-thalassaemia consisted of the five most common mutations: --^SEA, -α^3.7, -α^4.2, α^CS, and α^QS. Seven types of β-thalassaemia mutation were found in this study: CD41-42 (-TTCT) was the most frequent (28.47%), followed by 17 (A > T), −28 (A > G), and IVS-II-654 (C > T). The main abnormal haemoglobin genotype (HbE) and thalassaemia genotype (--^SEA, CD41-42 (-TTCT)) were consistent with those in other regions of China, but the carrier rate of β-thalassaemia in Sichuan was higher than that of α-thalassaemia.

Prevalence and genetic analysis of thalassemia in neonates in Wuhan area: a national megacity in central China

BACKGROUND

Thalassemia is one of the most common genetic diseases in southern China. Accurate population frequency data regarding the occurrence and distribution of thalassemia is important for designing appropriate prevention strategies of thalassemia.

OBJECTIVE

The aim of this study is to reveal the prevalence and the mutation spectrum of thalassemia in neonates in the Wuhan region of central China.

METHODS

About 3796 neonates in Wuhan area of China were analyzed by hematological and genetic analysis.

RESULTS

About 2174 subjects were genetically diagnosed as thalassemia carriers or patients, including 1415 cases of α-thalassemia (65.89%), 731 cases of β-thalassemia (33.62%), and 28 cases of α-composite β-thalassemia (1.29%). A total of 11 genotypes and 6 gene mutations were identified in α-thalassemia anomalies, with -^SEA/deletion (50.72%), -α^3.7/deletion (36.36%), and -α^4.2/deletion (7.38%) being the most common α-thalassemia mutations. β-thalassemia anomalies were associated with 17 genotypes and 12 gene mutations; IVS-2-654 mutation was the most common (41.18%), followed by CD41-42 (23.14%), CD17 (14.64%), CD26 (7.32%), and CD27-28 (4.58%) mutations. In addition, 13 genotypes were identified in α-composite β-thalassemia in thalassemia carrier, with the top six genotypes being IVS-2-654/N/-^SEA/αα (17.86%), CD17/N/-α^3.7/αα (17.86%), IVS-2-654/N/-α^3.7/αα (14.29%), CD41-42/N/-^SEA/αα (10.71%), CD71-72/N/-α^3.7/αα (7.14%), and Cap/N/-^SEA/αα (7.14%).

CONCLUSION

There was high heterogeneity and extensive spectrum of thalassemia in the neonates in Wuhan populations. The findings will be useful for genetic counseling and prenatal diagnosis of thalassemia in the Wuhan region.

Molecular characterization of thalassemia and hemoglobinopathy in Southeastern China

Thalassemia and hemoglobinopathy are two common inherited disorders, which are highly prevalent in southern China. However, there is little knowledge on the genotypes of thalassemia and hemoglobinopathy in Southeastern China. In this study, we present a large-scale genetic detection and molecular characterization of thalassemia and hemoglobinopathy in Fujian province, Southeastern China. A total of 189414 subjects screened for thalassemia were recruited, and the hemoglobin components and levels were investigated. Furthermore, suspected common thalassemia was identified, and the suspected rare forms of common thalassemias and hemoglobinopathy were detected. Among the total subjects screened, the overall prevalence of thalassemia and hemoglobinopathy was 6.8% and 0.26%, and rare α-thalassemia genotypes HKαα, –^THAI/αα and −α^27.6/αα, and novel β-thalassemia gene mutations CD90(G → T) and IVS-I-110(G > A) were identified. Additionally, Hb Q-Thailand hemoglobinopathy and five other types of hemoglobinopathies (Hb New York, Hb J-Bangkok, Hb G-Taipei, Hb G-Coushatta and Hb Maputo) were found. The results of this 10-year large-scale study demonstrate high prevalence of thalassemia with complicated gene mutations in Southeastern China, which provides valuable baseline data for genetic counseling and prenatal diagnosis. In addition to detection of common thalassemia genes, detection of rare thalassemia genotypes and hemoglobinopathies is recommended.

Analysis of Glucose-6-Phosphate Dehydrogenase Genetic Polymorphism in the Hakka Population in Southern China

Background

In southern China, glucose-6-phosphate dehydrogenase (G6PD) deficiency is a significant health problem. The aim of this study was to investigate the molecular epidemiological characteristic of the G6PD gene among Chinese Hakka in southern Guangdong province.

Material/Methods

We screened 611 unrelated subjects for G6PD genetic polymorphism analyzed by a gene chip analysis for common Chinese G6PD mutations. G-6-PD enzyme activity was determined by use of the G-6-PD quantitative detection kit.

Results

Seven mutation sites were detected from subjects in our study. G6PD Canton (c.1376 G→T)(33.06%), G6PD Kaiping (c.1388 G→A)(30.67%), and polymorphism (c.1311 C→T)(25.89%) account for 89.62% of mutations, followed by G6PD Gaohe (c.95 A→G)(5.97%), G6PD Chinese-5 (c.1024 C→T)(3.58%), G6PD Maewo (c.1360 C→T)(0.39%), and G6PD Viangchan (c.871G→A)(0.39%).

Conclusions

We studied the genetic polymorphisms and frequencies of G6PD gene in the Hakka population of Meizhou. Our results coincide with the results among the Chinese Jiangxi Hakka population. It was consistent with previous research reports on Chinese people. There were differences in the results of reports from some other Asian populations. Our results could be useful for future prevention and control of G6PD deficiency aimed at the Chinese Hakka population.

Molecular Spectrum of α- and β-Thalassemia Mutations in a Large Ethnic Hakka Population in Southern China

Thalassemia is one of the most prevalent inherited disorders in southern China. However, there have been few reports on molecular characterization of α- and β-thalassemia (α- and β-thal) in the large Hakka population living in Meizhou, a city with high incidence of thalassemia in China. A total of 11,631 in- and outpatients in the Hakka area were analyzed by DNA-based α- and β-thal testing. Of all the samples, 4280 mutant chromosomes were detected, accounting in a total of 35.98%, of which 2864 (24.82%) α-thal mutants were detected, 1268 (10.09%) β-thal mutants were detected, 148 (1.27%) α- and β-thal mutants were detected. The following mutations - -^SEA/αα (Southeast Asian deletion), β^A/β^A; αα/αα, IVS-II-654 (C>T) (HBB: c.316-197C>T)/β^A; αα/αα, codons 41/42 (-TCTT) (HBB: c.126_129delCTTT)/β^A; and -α^3.7/αα, β^A/β^A were the most common thalassemia genotypes. The most common thalassemia genotype in the Hakka population in Meizhou was α-thal. In order to reduce the incidence of severe thalassemia in children, a prevention and control strategy should be established based on the distribution data of thalassemia genotyping. Our findings provide a valuable reference for clinical institutions or local governments to reduce the prevalence of thalassemia in the subtropical regions in the world.

The prevalence and molecular characterization of (δβ)0 -thalassemia and hereditary persistence of fetal hemoglobin in the Chinese Zhuang population

Objective

To reveal the prevalence and molecular characterization of (δβ)⁰‐thalassemia [(δβ)⁰‐thal] and hereditary persistence of fetal hemoglobin (HPFH) in the Chinese Zhuang population.

Methods

A total of 105 subjects with fetal hemoglobin (Hb F) level ≥5% from 14 204 unrelated ones were selected for the study. Multiplex ligation dependent probe amplification was firstly used to analyze dosage changes of the β‐globin gene cluster for associated with (δβ)⁰‐thal and HPFH mutations. The gap polymerase chain reaction was then performed to identify the deletions using the respective flanking primers. Hematologic data were recorded and correlated with the molecular findings.

Results

Twenty‐one (0.15%) subjects were diagnosed with Chinese ^Gγ(^Aγδβ)⁰‐thal. Nine (0.06%) were diagnosed with Southeast Asia HPFH (SEA‐HPFH) deletion. Seventy‐five (0.53%) cases remained uncharacterized. Three genotypes for Chinese ^Gγ(^Aγδβ)⁰‐thal and SEA‐HPFH deletion were identified, respectively. The genotype‐phenotype relationships were discussed.

Conclusion

Our study for the first time demonstrated that (δβ)⁰ and HPFH were not rare events, and molecular characterized ^Gγ(^Aγδβ)⁰‐thal and HFPH mutations in the Chinese Zhuang population. The findings in our study will be useful in genetic counseling and prenatal diagnostic service of β‐thalassemia in this populations.

Scanning for α-Hemoglobin Variants by High-Resolution Melting Analysis

BACKGROUND

Definitive detection of hemoglobin (Hb) variants requires DNA sequencing. High-resolution melting (HRM) analysis of polymerase chain reaction (PCR) amplicons was applied to detect and discriminate among uncommon α-Hb variants found in Thailand.

METHODS

Uncommon suspected α-Hb variants observed in Hb typing were identified by sequencing of DNA from whole blood samples. Three pairs of PCR primers covering the mutation regions in the three α-globin exons then were used for PCR coupled with difference in HRM analysis to subtract out the concomitant melting profile of the normal allele in the heterozygous state.

RESULTS

DNA sequencing identified six heterozygous α-Hb variants, namely, Hb G-Waimanalo (HBA2: exon 2, codon 64 G>A), Hb J-Buda (HBA1: exon 2, codon 61 G>T), Hb Kurosaki (HBA2: exon 1; codon 7 A>G), Hb O-Indonesia (HBA1: exon 3 codon 116 G>A), Hb Q-India (HBA1:exon 2, codon 64 G>C), and Hb Q-Thailand (HBA1: exon 2 codon 74 G>C). Difference HRM analysis showed one temperature melting profile using exon 1 primer pair, four different profiles with exon 2 primer pair, and one profile with exon 3 primer pair.

CONCLUSIONS

PCR-HRM analysis was effective in detecting and discriminating among single point mutations causing six uncommon α-Hb variants in heterozygous individuals. The method can be applied for routine screening due to its simplicity and relatively low cost.

Prevalence and genetic analysis of α- and β-thalassemia in Baise region, a multi-ethnic region in southern China

Thalassemia is one of the most common hereditary blood disorders. Epidemiological data regarding the occurrence and distribution of thalassemia is important for designing appropriate prevention strategies. The objective of this study was to update and reveal the prevalence of thalassemia and mutation spectrum in the Baise region of southern China. We screened 47,500 individuals from Baise region by hematological and genetic analysis. Totally, 11,432 (24.07%) subjects were diagnosed as being carriers and patients of thalassemia, including 7290 (15.35%) subjects with α-thalassemia, 3152 (6.64%) subjects with β-thalassemia and 990 (2.08%) subjects with both α-thalassemia and β-thalassemia. Ten α-thalassemia mutations and 31 genotypes were identified in the α-thalassemia carriers and patients. Meanwhile, 13 β-thalassemia mutations and 26 genotypes were characterized in the β-thalassemia carriers and patients. Furthermore, the true prevalence of nondeletional mutations and Thailand type (-THAI) deletion mutation were first reported in this study. In addition, three cases of αα/ααα3.7, five cases of HKαα/αα and two rare β-globin mutations, -86 (G>C) and CD 121 (G>T) were first identified in the Chinese Zhuang ethnic populations. Our data indicated that there was great heterogeneity and extensive spectrum of thalassemias in the Baise populations. The findings will be useful for genetic counseling and prevention of severe thalassemia in this region.

Molecular epidemiological investigation of G6PD deficiency by a gene chip among Chinese Hakka of southern Jiangxi province

In southern China, glucose-6-phosphate dehydrogenase (G6PD) deficiency is a significant health problem, and the incidence ranged from 0.5 to 4.08% in different Chinese population. The aims of this study are to investigate the molecular epidemiological characteristic of the G6PD gene among Chinese Hakka in southern Jiangxi province. 2331 unrelated subjects were screened for G6PD deficiency by a fluorescent test. DNA from deficient individuals was analyzed by a gene chip analysis for thirteen common Chinese G6PD mutations. In total, 3.60% (82/2331; 95% CI 2.77-4.27) of the sample were found to be G6PD-deficient. Eight mutations were found from 80 samples. However, mutation(s) for the two remaining samples were unknown. The most common mutations were G6PD Canton (1376 G>T) and G6PD Kaiping (1388 G>A), and the following mutations were 1311 polymorphism (1311 C>T), G6PD Gaohe (95 A>G), G6PD Chinese-5 (1024 C>T), G6PD Maewo (1360 C>T), Shunde (592 C>T), G6PD Viangchan (871 G>A) and Chinese-3 (493 A>G). This is the first report of G6PD deficiency among Chinese Hakka population in Jiangxi province.

Molecular Epidemiological Investigation of Thalassemia in the Chengdu Region, Sichuan Province, Southwest China

Thalassemia is the most common inherited disease in southern China. However, this disorder is usually ignored by the health system in the Sichuan Province due to the lack of epidemiological data. To provide basic epidemiological data for thalassemia screening, genetic counseling, and prenatal diagnosis (PND) in the Chengdu region, a total of 3262 healthy subjects were assessed by complete blood count (CBC), reverse dot-blot gene chip, gap-polymerase chain reaction (gap-PCR), and PCR-DNA sequencing. A frequency of heterozygous thalassemia of 3.43% (112/3262) was found, of which 2.21% (72/3262) patients carried α-thalassemia (α-thal), 1.19% (39/3262) β-thalassemia (β-thal) and 0.3% (1/3262) hereditary persistence of fetal hemoglobin (Hb) (HPFH)/δβ-thalassemia (δβ-thal). Four types of α-thal mutations were found, the most prevalent being - -(SEA) (68.06%), followed by -α(3.7) (rightward deletion, 25.0%), Hb Quong Sze (Hb QS; HBA2: c.377 T > C) (4.17%), and -α(4.2) (leftward deletion, 2.78%). The seven β-thal mutations included: codons 41/42 (-TTCT), HBB: c.126_129delCTTT (13/39, 33.33%); codon 17 (A > T), HBB: c.52 A > T (11/39, 28.95%); IVS-II-654 (C > T), HBB: c.316-197 C > T (9/39, 23.68%); -28 (A > G), HBB: c.-78 A > G (3/39, 7.69%); -29 (A > G), HBB: c.-79 A > G (1/39, 2.56%); codons 27/28 (+C), HBB: c.84_85insC (1/39, 2.56%), and the rare IVS-II-850 (G > T), HBB: c.316-1 G > T (1/39, 2.56%). Only one case of the Southeast Asian HPFH deletion was found. This is the first detailed molecular epidemiological survey of thalassemia in the Chengdu region, Sichuan Province, People's Republic of China (PRC).

G6PD Deficiency and Hemoglobinopathies: Molecular Epidemiological Characteristics and Healthy Effects on Malaria Endemic Bioko Island, Equatorial Guinea

Background

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and hemoglobinopathies were the inherited conditions found mostly in African. However, few epidemiological data of these disorders was reported in Equatorial Guinea (EQG). This study aimed to assess the prevalence and healthy effects of G6PD deficiency and hemoglobinopathies among the people on malaria endemic Bioko Island, EQG.

Materials and Methods

Blood samples from 4,144 unrelated subjects were analyzed for G6PD deficieny by fluorescence spot test (FST), high-resolution melting assay and PCR-DNA sequencing. In addition, 1,186 samples were randomly selected from the 4,144 subjects for detection of hemoglobin S (HbS), HbC, and α-thalassemia deletion by complete blood count, PCR-DNA sequencing and reverse dot blot (RDB).

Results

The prevalence of malaria and anemia was 12.6% (522/4,144) and 32.8% (389/1,186), respectively. Overall, 8.7% subjects (359/4,144) were G6PD-deficient by FST, including 9.0% (249/2,758) males and 7.9% (110/1,386) females. Among the 359 G6PD-deficient individuals molecularly studied, the G6PD A^- (G202A/A376G) were detected in 356 cases (99.2%), G6PD Betica (T968C/A376G) in 3 cases. Among the 1,186 subjects, 201 cases were HbS heterozygotes, 35 cases were HbC heterozygotes, and 2 cases were HbCS double heterozygotes; 452 cases showed heterozygous α-thalassemia 3.7 kb deletion (-α^3.7 kb deletion) and 85 homozygous - α^3.7 kb deletion. The overall allele frequencies were HbS 17.1% (203/1186); HbC, 3.1% (37/1186); and –α^3.7 kb deletion 52.4% (622/1186), respectively.

Conclusions

High G6PD deficiency in this population indicate that diagnosis and management of G6PD deficiency is necessary on Bioko Island. Obligatory newborn screening, prenatal screening and counseling for these genetic disorders, especially HbS, are needed on the island.

Molecular epidemiological characterization and health burden of thalassemia in Jiangxi Province, P. R. China

BACKGROUND

Thalassemia is the most common inherited disease in southern China. However, this disorder is usually ignored by Jiangxi provincial health system and government due to lack of epidemiological data.

MATERIALS AND METHODS

A total of 9489 samples from Hakka Han and Gan-speaking Han in three geographical areas of Jiangxi Province were analyzed for both complete blood cell (CBC) count and reverse dot blot (RDB) gene chip for thalassemia.

RESULTS

1182 cases of suspected thalassemia carriers with microcytosis (MCV<82 fL) were found by CBC count, and were tested by RDB gene chip to reveal a total of 594 mutant chromosomes, including 433 α-thalassemia mutant chromosomes and 172 β-thalassemia mutant chromosomes. Our results indicated a higher prevalence of thalassemia with the heterozygote frequency of 9.49% in southern Jiangxi province, whereas the low frequency was found in middle (3.90%) and northern Jiangxi (2.63%).

CONCLUSIONS

Based on the epidemiological data, the estimated numbers of pregnancies in Jiangxi province in which the fetus is at risk for β-thalassemia major or intermedia, Bart's hydrops fetalis and Hb H disease are 34 (95% CI, 16 to 58), 79 (95% CI, 50 to 114) and 39 (95% CI, 27 to 58) per year, respectively. We suggested that prevention network of thalassemia should be established, especially in high prevalent southern Jiangxi (Hakka Han), including establishment of thalassemia database collection, hematological analysis laboratories, genetic counselling clinics, prenatal diagnosis centers and neonatal screening centers.

Prevalence and molecular characterization of structural hemoglobin variants in the Dongguan region of Guangdong province, southern China

The aim of the present study was to find the most prevalent structural hemoglobin (Hb) variants in southern China and to present hematological and molecular data of abnormal Hbs in the population from southern China. The type and frequency of structural Hb variants and their hematological and molecular characteristics were identified in 131 individuals from 30,848 unrelated partners who were referred to the prenatal clinic of Dongguan Maternal & Children Health Hospital, Dongguan, Guangdong, People's Republic of China (PRC) from 2011 to 2013. α-Globin or β-globin chain variants were screened using a capillary electrophoresis (CE) system, and α-globin or β-globin gene mutations were confirmed using sequencing techniques. The gene frequency of Hb variants was 0.4% (131/30,848). The most common α-globin variants were Hb Constant Spring (Hb CS, HBA2: c.427T > C) (0.2%), followed by Hb Q-Thailand (HBA1: c.223G > C) and Hb G-Honolulu (HBA2: c.91G > C). The most common β-globin variant was Hb E (HBB: c.79G > A) (0.09%), followed by Hb New York (HBB: c.341T > A). Our results provide a detailed prevalence and molecular characterization of abnormal Hbs in the population of the Dongguan region. These findings have important implications for a region with a high frequency of α- and β-thalassemias.

The prevalence and molecular spectrum of α- and β-globin gene mutations in 14,332 families of Guangdong Province, China

OBJECTIVE

To reveal the familial prevalence and molecular variation of α- and β-globin gene mutations in Guangdong Province.

METHODS

A total of 40,808 blood samples from 14,332 families were obtained and analyzed for both hematological and molecular parameters.

RESULTS

A high prevalence of α- and β-globin gene mutations was found. Overall, 17.70% of pregnant women, 15.94% of their husbands, 16.03% of neonates, and 16.83% of couples (pregnant women and their husbands) were heterozygous carriers of α- or β-thalassemia. The regions with the highest prevalence were the mountainous and western regions, followed by the Pearl River Delta; the region with the lowest prevalence was Chaoshan. The total familial carrier rate (both spouses were α- or β-thalassemia carriers) was 1.87%, and the individual carrier rates of α- and β-thalassemia were 1.68% and 0.20%, respectively. The total rate of moderate-to-severe fetal thalassemia was 12.78% among couples in which both parents were carriers.

CONCLUSIONS

There was a high prevalence of α- and β-thalassemia in Guangdong Province. This study will contribute to the development of thalassemia prevention and control strategies in Guangdong Province.

High resolution melting analysis: a rapid screening and typing tool for common β-thalassemia mutation in Chinese population

β-thalassemia is a common inherited disorder worldwide including southern China, and at least 45 distinct β-thalassemia mutations have been identified in China. High-resolution melting (HRM) assay was recently introduced as a rapid, inexpensive and effective method for genotyping. However, there was no systemic study on the diagnostic capability of HRM to identify β-thalassemia. Here, we used an improved HRM method to screen and type 12 common β-thalassemia mutations in Chinese, and the rapidity and reliability of this method was investigated. The whole PCR and HRM procedure could be completed in 40 min. The heterozygous mutations and 4 kinds of homozygous mutations could be readily differentiated from the melting curve except c.-78A>G heterozygote and c.-79A>G heterozygote. The diagnostic reliability of this HRM assay was evaluated on 756 pre-typed genomic DNA samples and 50 cases of blood spots on filter paper, which were collected from seven high prevalent provinces in southern China. If c.-78A>G heterozygote and c.-79A>G heterozygote were classified into the same group (c.-78&79 A>G heterozygote), the HRM method was in complete concordance with the reference method (reverse dot blot/DNA-sequencing). In a conclusion, the HRM method appears to be an accurate and sensitive method for the rapid screening and identification of β-thalassemia mutations. In the future, we suggest this technology to be used in neonatal blood spot screening program. It could enlarge the coverage of β-thalassemia screening program in China. At the same time, its value should be confirmed in prospectively clinical and epidemiological studies.