In 1948 Haldane first proposed that the high frequencies of thalassaemias in malaria-endemic regions were due to natural selection by malaria. Some of the highest frequencies of alpha+ -thalassaemia are found in the Pacific region of Melanesia. Consequently, Melanesia has provided a unique opportunity for an extensive study of the association between alpha+ -thalassaemia and malaria. Here we review the emergence of alpha+ -thalassaemia in this region and the research that has been carried out, both from the historical perspective and the most recent developments, which may give insight into the selection of alpha+ -thalassaemia by malaria.
Malaria/*epidemiology ; Melanesia/epidemiology ; alpha-Thalassemia/*epidemiology

Hemoglobins, Abnormal ; Humans ; Singapore/epidemiology* ; alpha-Thalassemia

OBJECTIVES: To investigate the distribution of genotypes of thalassemia in children in Guangxi, China. METHODS: A total of 30 417 children with positive results of thalassemia screening in the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region from January 2011 to December 2019 were enrolled. Single-tube multiplex PCR, agarose gel electrophoresis, and reverse dot blot hybridization technique were used for the detection of common α- and β-thalassemia genes. Gap-PCR or gene sequence analysis was performed for 2 703 children suspected of rare thalassemia. RESULTS: Among the 30 417 children with positive results of thalassemia screening, 23 214 (76.32%) were diagnosed with thalassemia, and the detection rates of α-thalassemia, β-thalassemia, and α-thalassemia with β-thalassemia were 47.77%, 23.75%, and 4.80% respectively. A total of 13 types of α-thalassemia alleles (18 480 alleles in total) were detected, mainly -- CONCLUSIONS There are diverse gene mutations and rich genotypes of thalassemia among children in Guangxi, and α-thalassemia is more common, with --
Child ; China/epidemiology* ; Genotype ; Heterozygote ; Humans ; Mutation ; alpha-Thalassemia/genetics* ; beta-Thalassemia/genetics*

OBJECTIVE: To investigate gene mutation types of thalassemia in the population of this area and the relationship between hematological phenotype and age in β-thalassemia. METHODS: 1 351 suspected cases of thalassemia were detected in the First Affiliated Hospital of Chengdu Medical College from June 2017 to June 2021. PCR-reverse dot blot hybridization(PCR-RDB) technique was used to detect the common α and β thalassemia gene types, then the data of MCV, MCH, MCHC and Hb of confirmed cases were collected. The heterozygotes of β-thalassemia were divided into 0-18 year group, 19-50 year group and >50 year group according to age, and the differences of hematological phenotypes among different groups were compared. RESULTS: Among the detected 1 351 samples， 523(38.71%) cases were diagnosed as thalassemia, 13 genotypes were detected in 260 cases (19.25%) with α-thalassemia; and 12 genotypes were detected in 252 cases (18.65%) with β-thalassemia; 9 genotypes were detected in 11 cases with αβ thalassemia. It was found that MCV and MCH were increased significantly in 0-18 year group, 19-50 year group and >50 year group, MCHC was highest in 0-18 year group, and Hb was the lowest in the >50 year group, and the difference was statistically significant（P<0.05）. CONCLUSION In this area, --^SEA/αα was the major genotype of α-thalassemia, and CD41-42 /N and IVS-II-654/N were the major genotypes of β-thalassemia. Morever, MCV and MCH were the lowest in the 0-18 year old group and the highest in the >50 years old group in heterozygotes of β-thalassemia. The influence of age on hematological parameters in the primary screening of thalassemia provides a certain reference value in clinical diagnosis and treatment.
China/epidemiology* ; Genotype ; Heterozygote ; Humans ; Mutation ; Phenotype ; alpha-Thalassemia/genetics* ; beta-Thalassemia/genetics*

OBJECTIVE: To analyze the incidence, genotype and hematological feature of hemoglobin H (HbH) disease in West Guangxi region. METHODS: A total of 1246 patients diagnosed with HbH disease from January 2013 to December 2018 in our hospital were enrolled. Red blood cell parameters, hemoglobin electrophoresis, Gap-polymerase china reaction (Gap-PCR) and polymerase chain reaction-reverse dot blot (PCR-RDB) techniques were used to detect the 6 common α-thalassemia mutations and 17 common β-thalassemia mutations. The results were compared with those of other regions. RESULTS: The detection rate for HbH disease was 5.66%. Among the 1246 patients, 614 (49.28%) had deletion-type HbH disease, including -α CONCLUSION The prevalence of HbH disease is high in West Guangxi region, and the main genotypeis non-deletion. α
China/epidemiology* ; Genotype ; Humans ; Mutation ; Prevalence ; alpha-Thalassemia/pathology* ; beta-Thalassemia/genetics*

OBJECTIVE: To analyze the gene defect types and distribution characteristics of α- and β-thalassemia in Lingui District of Guilin City, Guangxi, so as to provide scientific basis for genetic consultation and prevention measures. METHODS: A total of 6 496 suspected cases for screening the thalassemia during physical examination, premarital examination, pregnancy examination and hospitalization in the Second Affiliated Hospital of Guilin Medical University from May 2016 to October 2019 were analyzed. Gap-PCR, PCR-RDB and DNA sequencing techniques were used to detect the types and constituent ratios of gene defects in α- and β-thalassemia positive cases. RESULTS: Among 6 496 suspected patients, 1 363 were thalassemia carriers, the total positive rate was 20.98%. There were 677 cases of single-gene deletion and 26 cases of double-gene detetion on the deletional α-thalassemia, 115 cases of non-deletion α-thalassemia mutation and 4 cases of deletion plus mutation. The positive rate of α-thalassemia was 12.66%. There were 11 gene abnormalities for α-thalassemia, of which -- CONCLUSION Lingui district of Guilin city is a high incidence area of thalassemia. The mutation rate of α-thalassemia --
China/epidemiology* ; Female ; Genotype ; Heterozygote ; Humans ; Mutation ; Pregnancy ; alpha-Thalassemia/genetics* ; beta-Thalassemia/genetics*

OBJECTIVE: To study the distribution characteristics of thalassemia genotype in Han Population in Sanya of Hainan Province. METHODS: Gap PCR and reverse dot hybridization were used to detect and analyze the thalassemia gene in 572 suspected thalassemia carriers of Han Population in Sanya. RESULTS: Among the 572 Han Population in Sanya, 271 cases of thalassemia gene abnormality were detected, among which 161 cases were founded to be carriers of α-thalassemia gene. A total of 9 genotypes were detected, in the following order of the detection rate was －－^SEA/αα，－α^3.7/αα，－α^4.2/αα，－－^SEA/－α^3.7，－－^SEA/－α^4.2，－α^4.2/－α^4.2，－α^3.7/－α^4.2，－α^3.7/－α^3.7，－－^SEA/－－^SEA. Among them, the deletion type (－－^SEA/αα) in southeast Asia was the most common, accounting for 66 cases. 99 cases of β-thalassemia were detected, there were 7 genotypes, all of which were heterozygous. The order of the detection rate was CD41-42/βN, IVS-II-654/βN, CD17/βN, CD71-72/βN, -28/βN, －29/βN, CD27-28/βN. Among them, CD41-42/βN was the most common, accounting for 51 cases. In addition, 11 cases of combined α and β thalassemia were detected. Five kinds of genotypes were checked out, the order of detection rate was －α^3.7/αα composite CD41-42/βN, －－^SEA/αα composite IVS-II-654/βN, －α^4.2/－α^4.2 composite CD41-42/βN, －α^4.2/αα composite －29/βN , －－^SEA/ －α^4.2 composite CD41-42/βN. CONCLUSION Han Population in Sanya of Hainan Province is a high-risk population of thalassemia, the genotype characteristics are different from other areas with high incidence of thalassemia in China. The main type of α-thalassemia is the deficiency mutation of southeast Asia, while CD41-42 heterozygous mutation is the main type of β-thalassemia.
China/epidemiology* ; Genotype ; Heterozygote ; Humans ; Mutation ; alpha-Thalassemia/genetics* ; beta-Thalassemia

OBJECTIVE: To analyze the prevalence, genotype distribution and hematological characteristics of α,β-thalassaemia carriers in Huizhou area of Guangdong Province. METHODS: 10 809 carriers of simple β-thalassaemia and 1 757 carriers of α,β-thalassaemia were enrolled as our study cohort. The hematological parameters were detected by automated blood cell counters and automatic capillary electrophoresis. Suspension array technology, gap-polymerase chain reaction (gap-PCR) and PCR-reverse dot blot were used for the genotyping of thalassaemia carriers. RESULTS: The prevalence of α,β-thalassaemia in Huizhou area of Guangdong Province was 1.99%. A total of 62 genotypes were detected, and the most prevalent genotype was --^SEA/ αα, β^CD41-42/ β^N (19.29%), the next was --^SEA/ αα, β^IVS-II-654/ β^N (16.73%). Significant differences in mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were found between different genotype groups for simple β-thalassaemia and α,β-thalassaemia. Violin plots showed that carriers with co-inheritance of β-thalassaemia and mild α-thalassaemia expressed the lightest anemia, and carriers with co-inheritance of β-thalassaemia and hemoglobin H (Hb H) disease expressed the most severe anemia. CONCLUSION There is a high prevalence of α,β-thalassaemia in Huizhou area of Guangdong Province. Because of the lack of specific hematological makers for diagnosis of α,β-thalassaemia, it is necessary to distinguish it from simple β-thalassaemia by genotyping of α- and β-thalassaemia in order to correctly guide genetic counseling and prenatal disgnosis.
Pregnancy ; Female ; Humans ; beta-Thalassemia/genetics* ; Genotype ; Heterozygote ; Phenotype ; alpha-Thalassemia/genetics* ; China/epidemiology* ; Mutation

OBJECTIVE: To investigate the gene mutation and genotype distribution of thalassemia in the population of childbearing age in Chongzuo area of Guangxi. METHODS: Six α-thalassemia and 17 β-thalassemia gene mutations common in Chinese were detected by gap-polymerase chain reaction (gap-PCR) combined with agarose gel eletrophoresis and reserve dot bolt hybridization in 29 266 cases of child-bearing age suspected of thalassemia. RESULTS: A total of 19 128 (65.36%) cases were identified with thalassemia. The detection rate of α-thalassemia, β-thalassemia and α-combining β-thalassemia was 45.25% (13 242/29 266), 15.47% (4 526/29 266) and 4.65% (1 360/29 266), respectively. A total carrying rate of 8 kinds of α-thalassemia gene mutations was 26.74% (15 649/58 532), including 12.51% for --^SEA, followed by 5.70% for -α^3.7, and 0.24% for --^Thai. Among 32 α-thalassemia genotypes, the most common five were --^SEA/αα, -α^3.7/αα, α^CSα/αα, -α^4.2/αα and α^WSα/αα, accounting for 47.27%, 18.31%, 8.56%, 8.52% and 7.91%, respectively, as well as 0.97% for --^Thai/αα. A total carrying rate of 13 kinds of β-thalassemia gene mutations was 10.07% (5 897/58 532), including 3.63% for CD41-42, followed by 2.55% for CD17, and 0.003% for -50 (G>A). Among 17 β-thalassemia genotypes, the most common six were CD41-42/N, CD17/N, CD71-72/N, CD26/N, 28/N and IVSI-1/N, accounting for 36.15%, 25.81%, 9.43%, 8.18%, 8.09% and 7.75%. The homozygous genotype CD26/CD26 [hemoglobin (Hb): 121 g/L] and -28/-28 (Hb: 56 g/L) were respectively detected in one case, and double heterozygous genotype were detected in 5 cases, including 3 cases of CD41-42/CD26 (Hb: 41 g/L, 51 g/L, 63 g/L, respectively), 1 case of -28/IVSI-1 (Hb: 53 g/L), and 1 case of CD71-72/CD26 (Hb: 89 g/L), in which patients with moderate or severe anemia had a history of blood transfusion. Among 104 α-combining β-thalassemia genotypes, the most common were --^SEA/αα, -α^3.7/αα combining CD41-42/N and --^SEA/αα combining CD17/N, accounting for 12.13%, 9.63% and 9.26%, respectively. In addition, 1 case of --^SEA/-α^3.7 combining -28/IVSI-1 (Hb: 83 g/L) and 1 case of -α^3.7/αα combining CD41-42/ CD41-42 (Hb: 110 g/L) were detected without history of blood transfusion, while 1 case of α^WSα/αα combining CD41-42/CD17 (Hb: 79 g/L) and 1 case of --^SEA/αα combining CD17/-28 (Hb: 46 g/L) were detected with history. CONCLUSIONS The detection rate of thalassemia genes is high and the mutations are diverse in the population of childbearing age in Chongzuo area of Guangxi. The common deletion genotype is --^SEA/αα in α-thalassemia and CD41-42/N in β-thalassemia, and deletion genotype --^Thai is not rare. There is a certain incidence of intermediate and severe β-thalassemia, and most patients require transfusion therapy. The results are beneficial for genetic consultation and intervention of thalassemia.
Humans ; beta-Thalassemia/genetics* ; alpha-Thalassemia/genetics* ; Dipeptidyl Peptidase 4/genetics* ; China/epidemiology* ; Genotype ; Mutation

OBJECTIVE: This study was aimed at investigating the carrier rate of, and molecular variation in, α- and β-globin gene mutations in Hunan Province. METHODS: We recruited 25,946 individuals attending premarital screening from 42 districts and counties in all 14 cities of Hunan Province. Hematological screening was performed, and molecular parameters were assessed. RESULTS: The overall carrier rate of thalassemia was 7.1%, including 4.83% for α-thalassemia, 2.15% for β-thalassemia, and 0.12% for both α- and β-thalassemia. The highest carrier rate of thalassemia was in Yongzhou (14.57%). The most abundant genotype of α-thalassemia and β-thalassemia was -α ^3.7/αα (50.23%) and β ^IVS-II-654/β ^N (28.23%), respectively. Four α-globin mutations [CD108 (ACC>AAC), CAP +29 (G>C), Hb Agrinio and Hb Cervantes] and six β-globin mutations [CAP +8 (C>T), IVS-II-848 (C>T), -56 (G>C), beta nt-77 (G>C), codon 20/21 (-TGGA) and Hb Knossos] had not previously been identified in China. Furthermore, this study provides the first report of the carrier rates of abnormal hemoglobin variants and α-globin triplication in Hunan Province, which were 0.49% and 1.99%, respectively. CONCLUSION Our study demonstrates the high complexity and diversity of thalassemia gene mutations in the Hunan population. The results should facilitate genetic counselling and the prevention of severe thalassemia in this region.
Humans ; beta-Thalassemia/genetics* ; alpha-Thalassemia/genetics* ; Hemoglobinopathies/genetics* ; China/epidemiology* ; High-Throughput Nucleotide Sequencing