Prevalence Of Α-thalassemia Research Articles

A particular focus on the prevalence of α-thalassemia and β-thalassemia among pregnant women in Changsha County, Hunan Province.

Thalassemia is a inherited monogenic blood disorder and more prevalent in southern China. In this study, Our aim was to elucidate the molecular spectrum and phenotypic features of thalassemia in pregnant women in Changsha County. Next-generation sequencing (NGS) was conducted for 38,810 pregnant women to diagnose thalassemia in Changsha County. Further analysis of hematological parameters was conducted on subjects who had not previously undergone thalassemia screening in other hospitals. In this study, 2,208 (5.69%) pregnant women were diagnosed as carriers of thalassemia using NGS analysis. Among 1,594 cases of α-thalassemia, 23 genotypes were identified, and among 578 cases of β-thalassemia, 22 genotypes were detected. Additionally, 18 genotypes were detected among 36 cases of composite α- and β-thalassemia. Among all carriers of thalassemia, 8 rare α-mutations and 11 rare β-mutations were found in the study population. Notably, pregnant women diagnosed as carriers of thalassemia tended to have lower hemoglobin levels. Furthermore, multivariable logistic regression analysis indicates that the values of MCV and MCH have the greatest impact on genetic diagnosis. Our study has provided detailed genotypes and hematological parameters of thalassemia in pregnant women in Changsha county and reveal that certain abnormal blood parameters have a remarkably impact on genetic diagnosis results. Furthermore, our data suggest that combining hemoglobin electrophoresis and NGS provides a powerful tool for prenatal diagnosis, which will increase the accuracy of clinical diagnosis of thalassemia.

Prevalence and Genetic Analysis of Thalassemia and Hemoglobinopathy in Different Ethnic Groups and Regions in Hainan Island, Southeast China.

Background: There are limited studies on the molecular profile of thalassemia in Hainan, the free trade island in China. Our aim was to reveal the prevalence and molecular mutation spectrum of thalassemia in different ethnic groups and regions of Hainan through a large sample study for the first time. Methods: A total of 231,596 individuals from 19 cities and counties in Hainan were screened by hematological parameter analysis, and further genetic analysis was performed on individuals with MCV less than 82 fL. Results: Totally, 31,780 (13.72%) subjects were diagnosed as thalassemia carriers. The overall prevalence of α-thalassemia, β-thalassemia, and α+β-thalassemia were 11.04%, 1.48%, and 1.20%, respectively. We further analyzed the molecular profiles of thalassemia in various ethnic groups and mainly compared the difference between Han and Li. The results showed that the frequency of thalassemia in the Li population (47.03%) was much higher than that in Han (9.37%). Except for β-thalassemia (1.31% of Li vs. 1.47% of Han), the frequencies of α-thalassemia (39.59% of Li vs. 7.35% of Han) and α+β-thalassemia (6.13% of Li vs. 0.56% of Han) in the Li were obviously higher than those in Han. The high-frequent genotypes of α-thalassemia in Han were αα/--SEA (25.55%), -α3.7/αα (22.17%), -α4.2/αα (21.59%), αWSα/αα (8.93%), and -α3.7/-α4.2 (4.17%) and those of Li were -α4.2/αα (17.24%), -α3.7/αα (17.16%), -α3.7/-α4.2 (15.09%), αWSα/αα (9.69%), and αWSα/-α3.7 (8.06%), respectively. The αα/--SEA was the highest genotype of α-thalassemia in Han but only accounted for 1.87% in Li. For β-thalassemia, the top three high-frequent genotypes in both Han and Li were βCD41/42(-TTCT)/βN, β-28(A>G)/βN, and βIVS-Ⅱ-654(C>T)/βN, but the frequency of βCD41/42(-TTCT)/βN in Li (90.96%) was much higher than that in Han (56.32%) and the data reported in other provinces of China. Additionally, the prevalence of thalassemia ranged from 8.16% to 34.35% in Hainan, Wuzhishan, Baoting, Qiongzhong, and Baisha have a higher prevalence than other areas. Conclusion: Our study revealed the characteristics of ethnic and regional differences in the prevalence of thalassemia in the childbearing age population of Hainan for the first time, indicating that the prevalence of thalassemia among Li nationality is the highest in China. Those findings will be useful for genetic counseling and the prevention of thalassemia.

Prevalence and genetic analysis of thalassemia in childbearing age population of Hainan, The Free Trade Island in Southern China.

BackgroundHainan has one of the high incidences of thalassemia in China, but the epidemiological data in the whole province has not been reported yet. The objective of our study was to reveal the true prevalence and molecular mutation spectrum of thalassemia in the population of Hainan who are of childbearing age.MethodsWe screened 166,936 individuals from 19 cities and counties in Hainan by hematological parameters analysis, and further conducted genetic analysis for individuals whose MCV was less than 82fL.ResultsIn total, 21,619 (12.95%) subjects were diagnosed as thalassemia carriers or patients. The overall prevalence of α‐thalassemia, β‐thalassemia, and α+β‐thalassemia were 10.39%, 1.38%, and 1.18%, respectively. Eleven α‐thalassemia mutations and sixteen β‐thalassemia mutations were identified. The high‐frequent genotypes of α‐thalassemia were ‐α3.7/αα (19.70%), ‐α4.2/αα (19.39%), αα/‐‐SEA (15.60%), αWSα/αα (9.24%), and ‐α3.7/‐α4.2 (8.90%), and those of β‐thalassemia were βCD41/42(−TTCT)/βN (58.92%), β−28(A>G)/βN (16.05%), βIVS−Ⅱ−654(C>T)/βN (8.42%), βCD71/72(+A)/βN (6.03%), βCD17(A>T)/βN (5.47%), and βCD26 (GAG>AAG)/βN (2.69%). In addition, the frequencies and hematological profiles of many rare mutations of α‐ [Fusion, HKαα, αααanti4.2, IVS‐II‐55 (T>G), IVS‐II‐119 (−G,+CTCGGCCC)] and β‐globin genes [−50 (G>A), IVS‐Ⅱ‐81 (C>T)] in Hainan were reported for the first time.ConclusionOur study revealed the high prevalence and extensive molecular spectrum of thalassemia in childbearing age population of Hainan, suggesting thalassemia in Hainan ranks second in prevalence among all regions in China. The findings will be useful for genetic counseling and prevention of thalassemia.

Prevalence of Alpha(α)-Thalassemia in Southeast Asia (2010-2020): A Meta-Analysis Involving 83,674 Subjects.

Alpha(α)-thalassemia is a blood disorder caused by many types of inheritable α-globin gene mutations which causes no-to-severe clinical symptoms, such as Hb Bart’s hydrops fetalis that leads to early foetal death. Therefore, the aim of this meta-analysis was to provide an update from year 2010 to 2020 on the prevalence of α-thalassemia in Southeast Asia. A systematic literature search was performed using PubMed and SCOPUS databases for related studies published from 2010 to 2020, based on specified inclusion and exclusion criteria. Heterogeneity of included studies was examined with the I2 index and Q-test. Funnel plots and Egger’s tests were performed in order to determine publication bias in this meta-analysis. Twenty-nine studies with 83,674 subjects were included and pooled prevalence rates in this meta-analysis were calculated using random effect models based on high observed heterogeneity (I2 > 99.5, p-value < 0.1). Overall, the prevalence of α-thalassemia is 22.6%. The highest α-thalassemia prevalence was observed in Vietnam (51.5%) followed by Cambodia (39.5%), Laos (26.8%), Thailand (20.1%), and Malaysia (17.3%). No publication bias was detected. Conclusions: This meta-analysis suggested that a high prevalence of α-thalassemia occurred in selected Southeast Asia countries. This meta-analysis data are useful for designing thalassemia screening programs and improve the disease management.

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.

Prevalence of α-Thalassemia in the Egyptian Population

Hemoglobinopathies are the most common monogenic diseases in the world, causing many health problems worldwide. In Egypt, thalassemia is the most common cause of chronic hemolytic anemia and correlated with significant morbidity and mortality. One thousand Egyptian newborns were screened to detect α-thalassemia (α-thal) deletions using polymerase chain reaction (PCR)-based DNA analysis of cord blood samples. Ninety-one cases (9.1%) of the studied samples were proved to have at least one of the α genes deleted and 851 cases (85.1%) were normal by PCR analysis, while 58 samples (5.8%) failed to be amplified so further DNA analysis could not be done. In the studied group with α gene deletions, we found different types including silent carriers with only one α-globin gene deleted (3.1%), α-thal trait with two α-globin genes deleted (4.2%), Hb H disease with three α-globin genes deleted (1.8%) and no cases carrying Hb Bart’s disease with loss of four α-globin genes. We determined the deletional spectrum of α-thal, which might be used in the future for molecular investigations of the disease in susceptible patients in our population.

The prevalence of thalassemia in mainland China: evidence from epidemiological surveys

Comprehensive data regarding the epidemiology and prevalence of thalassemia in mainland China are lacking. To assess the prevalence of thalassemia, we performed a meta-analysis including 16 articles published from 1981 to 2015. The overall prevalence of α-thalassemia, β-thalassemia and α + β-thalassemia was 7.88%, 2.21% and 0.48%, respectively. Trends in thalassemia prevalence in mainland China were not steady; a prevalence map based on a geographic information system (GIS) showed that the geographic distribution of thalassemia was highest in the south of China and decreased from south to north. Additionally, the most common α- and β-globin gene mutation was --SEA and CD41/42, respectively. The current study provides valuable information regarding epidemiology and intervention and supports the planning, implementation and management of prevention programmes for public health.

The Prevalence of α-Thalassemia and Its Relation to Plasmodium falciparum Infection in Patients Presenting to Clinics in Two Distinct Ecological Zones in Ghana

Thalassemia and sickle cell disease constitute the most monogenic hemoglobin (Hb) disorders worldwide. Clinical symptoms of α+-thalassemia (α+-thal) are related to inadequate Hb production and accumulation of β- and/or γ-globin subunits. The association of thalassemia with malaria remains contentious, though from its distribution it appears to have offered some protection against the disease. Data on the prevalence of thalassemia in Ghana and its link with malaria is scanty and restricted. It was an objective of this cross-sectional study to determine the prevalence of thalassemia in areas representing two of Ghana’s distinct ecological zones. The relationship between thalassemia and Plasmodium falciparium (P. falciparum) infection was also ascertained. Overall, 277 patients presenting to health facilities in the study areas were recruited to participate. Tests were carried out to determine the presence of α+-thal, sickle cell and malaria parasites in the blood samples of participants. The outcome of this study showed an α+-thal frequency of 19.9% for heterozygotes (−α/αα) and 6.8% for homozygotes (−α/−α). Plasmodium falciparum was detected in 17.7% of the overall study population and 14.9% in those with α+-thal. No association was observed between those with α+-thal and the study sites (p > 0.05). A test of the Hardy-Weinberg law yielded no significant difference (p < 0.001). Findings from this study suggest a modest distribution of α+-thal in Ghana with no bias to the ecological zones. Although the prevalence and parasite density were relatively low in those with the disorder, no association was found between them.

Distribution of alpha-thalassemia mutations in Iranian population

BackgroundAlpha-thalassemia as one of the most common monogenetic disorders is widely spread over the Mediterranean, Southeast Asian, and Middle Eastern populations, including Iran. Although beta-thalassemia is much more common than alpha-thalassemia, alpha-thalassemia is still one of the main health problems in Iran with different mutation frequencies in various ethnic groups. So the evaluation of alpha-thalassemia mutations could be helpful to detect carriers as well as prevention strategy in Iranian population.ObjectivesThe aim of this study was to investigate the spectrum and frequencies of alpha-globin mutations in different ethnic groups of southern Iran.Materials and methodsCommon alpha-globin mutations were evaluated in 4010 Iranian population using a reverse dot blot for all point mutations and gap-polymerase chain reaction.ResultsOut of all individuals, 3993 were distinguished as carriers of alpha-thalassemia mutations. Thirteen types of alpha-thalassemia mutations were discovered. Allele of α3.7 mutation was the most prevalent (43.84%) followed by the αIVS1/−5NT allele with the prevalence of 4.91%. The less frequent alleles were Hb ICARIA and αcodon16 with the prevalence of 0.04 and 0.01%, respectively.ConclusionOur findings are essential for carrier screening, genetic counseling, and prenatal diagnosis in order to decrease the prevalence of α-thalassemia in Iran which is one of the goals of the national screening program.

Alpha thalassemia protects sickle cell anemia patients from macro-albuminuria through its effects on red blood cell rheological properties

While chronic hemolysis has been suspected to be involved in the development of glomerulopathy in patients with sickle cell anemia (SCA), no study focused on the implications of blood rheology. Ninety-six adults with SCA at steady state were included in the present cross-sectional study. Three categories were defined: normo-albuminuria (NORMO, n = 41), micro-albuminuria (MICRO, n = 23) and macro-albuminuria (MACRO, n = 32). Blood was sampled to measure hematological and hemorheological parameters, and genomic DNA extraction was performed to detect the presence of α-thalassemia. The prevalence of α-thalassemia was lower in the MACRO group compared with the two other groups. Anemia was more severe in the MACRO compared with the NORMO group leading the former group to exhibit decreased blood viscosity. Red blood cell deformability was lower and red blood cell aggregates strength was greater in the MACRO compared to the two other groups, and this was directly attributed to the lower frequency of α-thalassemia in the former group. Our results show the protective role of α-thalassemia against the development of sickle cell glomerulopathy, and strongly suggest that this protection is mediated through the decrease of anemia, the increase of RBC deformability and the lowering of the RBC aggregates strength.

Half of the Emirati Population Has Abnormal Red Cell Parameters: Challenges for Standards and Screening Guidelines

In populations with high prevalences of iron deficiency and thalassemia trait, many apparently healthy individuals have abnormal erythroid parameters, which may cause diagnostic problems in clinical practice. We studied the prevalence and causes of red cell parameter values outside their reference ranges in 394 healthy individuals of Bedouin Arab origin, who had complete blood counts (CBCs), hemoglobin (Hb) analyses and serum ferritin tests done. Their mean age ± standard deviation (SD) was 24.8 ± 4.9 years and 51.8% were females. Overall, 53.0% (209/394) had low Hb, MCV or MCH or high RDW. Anemia was present in 27.0% (55/204) of the women and 3.0% (6/190) of the men. Overall prevalence of MCV <80.0 fL was 45.0% (176/394) and MCH <27.0 pg was 48.0% (190/394); RDW >14.0% was found in 21.0% (43/204) of women and 7.0% (14/190) of men. Of the women, 16.0% had iron deficiency anemia (33/204) and 65.0% had ferritin values of <30.0 μg/L (133/204). The estimated prevalence of α-thalassemia (α-thal) trait in men was 32.0% (60/190) and that of β-thalassemia (β-thal) trait in both sexes was 3.0% (12/394). In conclusion, half of the healthy Emirati population have abnormal CBC values. For clinical purposes, they require reference standards for red cells that are derived from their own population. Screening of women for iron deficiency is justified due to a high prevalence of iron deficiency.

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 - α3.7 , - α4.2 , - α20.5 , — SEA and — MED deletions but only the - α3.7 allele was detected. The - α3.7 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 - α3.7 / αα, - α3.7 /- α3.7 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.

Determination of beta-globin gene cluster haplotypes and prevalence of alpha-thalassemia in sickle cell anemia patients in Venezuela.

Sickle cell anemia and alpha-thalassemia have a heterogeneous distribution in Venezuela with a high frequency in the coastal area (sea level) and few cases in the mountains. Most of our population is an ethnic admixture of Europeans (Spaniards colonists), Africans (slaves), and Amerindians. The purpose of our study was to determine the origin of the beta(s) globin haplotype, age and survival dependency, and the admixture among the different African groups in our population. The alpha(3.7) globin gene deletion status was also studied and found in a very high frequency. DNA from peripheral blood of 191 non-related patients (81 with HbS homozygous and 15 patients compound heterozygous for HbS, HbC, HbD with beta-thalassemia, and 95 with sickle cell trait) were studied. The beta(s) chromosome was linked 51% to the Benin Haplotype, 29.5% with the CAR, 12.5% to the Senegal, and 2.5% to the Cameroon. We did not find any significant difference between the haplotype distribution among adults and children and among sickle cell patients and traits. Only 8.6% of the patients have homozygosity for the Benin haplotype. These results show a very high frequency of admixture in our African origin population.

Regional Variations in Sickle Cell Anemia in Saudi Arabia

ABSTRACT We examined mean corpuscular volume (MCV), fetal hemoglobin (HbF) levels, and severity of clinical disease in 81 patients with sickle cell anemia from various regions of Saudi Arabia. We f...

A-Thalassemia

• αThalassemia is common in southeast Asia and the Mediterranean, where the predominant lesion seems to be a deletion of one or more of the four gene loci responsible for αglobin chain production. In the United States, the prevalence of αthalassemia in blacks was once thought to be low, but more recent studies show that the prevalence of αthalassemia is high. We measured the globin chain synthetic ratios in 144 black Americans to determine the prevalence and hematologic manifestations of αthalassemia in this population. There were 120 subjects with a mean synthetic ratio of 0.986 ± 0.04, with a range of 0.90 to 1.06; these were classified as normal. Five subjects were found to have βthalassemia; 19 subjects had mild α-thalassemia. The overall gene frequency for α-thalassemia was estimated to be 0.07 in this population. The hemoglobin values of subjects with mild α-thalassemia were not statistically significantly different from normal black or white control subjects of the same sex, but there was a significant decrease in the mean corpuscular volume and in the mean corpuscular hemoglobin value. (<i>Arch Intern Med</i>1982;142:1280-1282)