| Background and ObjectionHemoglobin disease (hemoglobinopathy) is an inherited disease which resulting from abnormal expression of globin gene on the quality and quantity. It can be divided into two categories:one is the abnormal hemoglobin (hemoglobin variant), result in abnormal structure of globin chain. Some abnormal hemoglobin showed the hematological phenotype of thalassemia, such as abnormal hemoglobin E (Hb E); another hemoglobinopathy, thalassemia, is due to expression reducing of certain types of globin gene. The clinical manifestations synthesis is hemolytic anemia for the imbalance of globin chain; hereditary the persistence of fetal hemoglobin (HPFH), result in globin synthesis abnormalities, usually be classified into thalassemia.Up to December2011, human variant database (http://globin.bx.psu.edu), had reported a total of1513kinds of globin gene mutation, including435kinds of thalassemia1128kinds of abnormal hemoglobin in the world. The World Health Organization reported about150million people which carried the genes of the hemoglobin disorders in the world, which mainly distributed tropical and subtropical regions. Hemoglobinopathy was the most common single gene disorders in the world. According to previous reports, the incidence of hemoglobinpathy varied with the ethnic group and geographic region, which caused serious economic burden and society burden in the whole society and the patient’s families. Hemoglobin occurred in China. Hemoglobinpathy was common in the provinces in the southern region of China’s Yangtze River, especially in Guangxi, Guangdong and Hainan provinces. The high incidence of hemoglobin disease was a serious public health problem in these areas. According to our knowledge, the incidence and genotypes varied with different regions, different races and different ethnic groups. Mutation, migration, selection, integration, drift, isolation and other factors can cause the genetic diversity and distribution of differences in hemoglobin disease.The eastern region of Guangdong Province generally included five regions as follow:Chaozhou, Shantou, Jieyang, Shanwei and Meizhou. It was the main settlements of two kinds of Guangdong Han, Hakka Han and Teochew Han. Total1577.4million people lived in the area, which accounting for21.04percent of all people in Guangdong province. The population density (1005people/km2) was higher than the provincial average population density. The area is one of the most densely populated areas in P.R.China.Aim to investigate prevalence and genotype of hemoglobinopathy in Hakka Han and Teochew Han in the eastern Guangdong Province. A total of26,679people, aged from5-70years old, attended the epidemiological investigation for hemoglobinopathies. All samples were analyzed by combined genotype analysis and hematologic phenotype analysis. This study described the prevalence and genotypes distribution of Hemoglobinopathies (abnormal hemoglobin, thalassemia, HPFH and δβ thalassemia) in the Chaoshan Han and Hakka Han in the area. At the same time, we tried to analyze the relationship among incidence of hemoglobin diseases, genotypes, settlement and ethnic group from the views of geography, population migration and genetics. In addition, in this study, we reported three kinds of hemoglobin disease which were first discovered in the China.Methods and materials1. Population samples:Between March2009and June2010,2mL peripheral blood sample was collected from each subject in Chaozhou area, Guangdong Province (two counties and one district). All sample of foreigner was excluded in our study based on the results of survey of native place. One of these study population of Chaozhou area included11,450’health’subjects.100%subjects were Chaoshan native.Their age ranged from9to65years old. Between February2011to June2011,2mL peripheral blood samples was collected from each subject aged from5to70years old. All sample of foreigner was excluded in our study based on the results of survey of native place.100%of the subjects were Hakka people. This study population included15229’health’ subjects in Meizhou area, Guangdong Province (six counties and one district).2. Haematological analysis:(1)Abnormal hemoglobin:The abnormal Hb screening was carried out by electrophoresis on cellulose acetate (pH8.6). According to the results of electrophoresis, the positive samples were detected by full blood counts (FBCs) and hemoglobin peptide chain analysis. The genotype of abnormal hemoglobin was analyzed by PCR-DNA sequencing. At the same time, these positive samples were identified for thalassemia by Gap-PCR and PCR-RDB.(2) Thalassemia:Total3283samples were measured by FBCs. The positive criteria that indicated the possibility of thalassemia heterozygote was mean corpuscular volume (MCV)<82fL. All positive samples (MCV<82fL) were identified by a kind of α/β thalassemia gene chip.(3) HPFH and δβ-thalassemia:Positive criteria that indicated the possibility of HPFH and8p-thalassemia was Hb F>5%. The multiplex ligation-dependent probe amplification was used to detect the gross deletion in β-globin gene of the positive samples.3. Satastical analysis:Statistical analyses were conducted with the SPSS16.0statistical software. Comparison of the prevalence of Meizhou area, Chaozhou area and other area of previous reports was conduced by Pearson x2test with Bonferroni adjustment for multiple testing. P<0.05was considered statistically difference. The prevalance of different hemoglobinpathy alleles was caculated from the modified Hardy-Weinberg formula.Results:Prevalence and genotype of abnormal hemoglobin Out of the total study population of11,450in Chaozhou area,41cases of hemoglobin variants were found by hemoglobin electrophoresis. The incidence of abnormal Hb was0.358%(41/11,450) in chaozhou area of eastern Guangdong, including five cases of Hb G-Waimanalo(12.2%,5/41), four cases of Hb G-Chinese (9.8%,4/41), four cases of Hb Ottawa (9.8%,4/41), two cases of Hb J-Wenchang-Wuming(4.9%,2/41), four cases of Hb Q-Thailand(9.8%,4/41), two cases of Hb New York(4.9%,2/41), three cases of Hb J-Bangkok (7.3%,3/41)and Seventeen cases of Hb E(41.5%,17/41).73cases of hemoglobin variants were found from15229people in Meizhou area. The incidence of abnormal Hb was0.479%(73/15229). The percent Of Hb E (24.7%,18/73) and Hb Q-Thailand (17.8%,13/73) were the first and the second in the abnormal hemoglobin. The percent Of Hb New York (16.4%,12/73) and Hb G-Chinese (16.4%,12/73) were third and fourth. These four kinds of abnormal hemoglobin were the mainly composition (68.5%) of our founding. The other six kinds of abnormal hemoglobin included one cases of J-Broussais (1.4%,1/73), two four cases of Hb J-Wenchang-Wuming (5.5%,4/73), seven cases of Hb J-Bangkok (9.6%,7/73), two cases of Queens (2.7%,2/73), one cases of Hb G-Waimanalo (1.4%,1/73) and three cases of Hb G-Siriraj (4.1%,3/73). The prevalence of Meizhou area was higher than the prevalence of Chaozhuo area.The prevalence and genotype distribution of thalassemiaThe prevalence was6.12%(103/1683) in Chaozhou area and was11.5%(184/1600) in Meizhou area. The prevalence of Meizhou area was higher than Chaozhou area.The incidence of a-thalassemia was4.63%(78/1683) in Chaozhou area. The percentage was75%(78/103) in all thalassemia samples. The Southeast Asian type of deletion (--SEA) was the most common genotype. The second genotype was-α3.7. The genotypes of all a-thalassemia samples were deletion form. Not any mutation genotype was found in Chaozhou people. The incidence of α-thalassemia was8.44%(135/1600) in Meizhou area. These samples included132cases of α-thalassemia deletion. The incidence of a-thalassemia deletion was8.25%(132/1600). Consistent with Chaozhou people, the Southeast Asian type of deletion (--SEA) was the most common genotype in Meizhou area, the second genotype was-α3.7. Not consistent with chaozhu area, two kinds of a-thalassemia mutation genotypes were found in Meizhou area. These samples included two cases of QS and a cases of CS.The prevalence of β-thalassemia was1.49%(25/1683) in Chaozho area, lower than2.81%(45/1600) in Meizhou area. Consistent with previous reports, the β-thalassemia genotype of Chaozhou area and Meizhou area was similar to of HK and other area of Guangdong. The mainly genotypes of P-thalassemia in the two area were CD41-42-TCTT and IVS-II-654C>T.HPFH and δβ-thalassemiaFour cases of Hb F>5%samples were found in our study, which included two cases of HPFH-7, a case of Dutch I12.6kb deletion thalassemia and a case of Belgian Gγ(Aγδβ)-thalassemia. The Dutch I12.6kb deletion thalassemia and Belgian Gγ(Aγδβ)-thalassemia were never reported in China. These two cases were first reported.ConclusionHakka people and Chaozhou people were the main composition of the population in eastern Guangdong area. Meizhou area was the main settlement of Hakka people. Chaozhou area was the main settlement of Chaoshan people. According to the reports of historical information, not only Hakka people but also Chaozhou people were a mix Han population including ancient Han migrants from Northern China and Guyue people. Up to day, there were not intimate and systemic molecular epidemiological data of haemoglobinopathies of Chaoshan people and Hakka people. In our study, we used a strategy that combined phenotypes/molecular screening with genotyping to investigate the prevalence and molecular characters of haemoglobinopathies of Chaoshan people and Hakka people. The results of our study indicated that there were different molecular epidemiological characters of haemoglobinopathies in Chaozhou area and Meizhou area.Abnormal hemoglobinIn the study,11,450subjects of Chaozhou area attended the screening program for abnormal hemoglobin, of which41cases of abnormal hemoglobin were found. The prevalence of abnormal hemoglobin was0.358%(41/11450) in Chaozhou area. The incidence of Chaozhou area was similar to the average of Guangdong province (0.368%) and average of7provinces in the southern region of the Yangtze River (0.330%). There was no significance statistically between them (Chaozhou v average of Guangdong province:P>0.05)(Chaozhou v average of southern region of the Yangtze River:P>0.05). The data was also consistent with previous report of Chaoshan people in Shantou area in the eighties of the19th century (0.333%)(P>0.05). It was higher than the average0.171%of7provinces in the northern region of the Yangtze River (.P<0.05).15229Hakka people received the abnormal hemoglobin screening, of which73cases of abnormal hemoglobin were found. The prevalence was0.479%in Meizhou area. The incidence of our study was lower than the prevalence (0.575%) of Meizhou area which was reported in the eighties of the19th century, but it was no significance statistically different between them (P>0.05). The incidence of Meizhou area was higher than the average of Guangdong province (0.368%)(P<0.05), the average of7provinces in the southern region of the Yangtze River (0.330%)(P<0.05) and the average0.171%of7provinces in the northern region of the Yangtze River (P<0.05). It incidence of Meizhou was only lower than Yunan province (5.94%)(P<0.05). There was no significance statistically (P>0.05) between Chaozhou area and Meizhou area.The main subgroups of abnormal hemoglobin were E group and GD group in the population in eastern Guangdong (Chaoshan people and Hakka people). In Chaozhou area, the percentage of E group of abnormal hemoglobin was41.9%, the percentage of GD group of abnormal hemoglobin was31.7%. In Hakka people, E group of abnormal hemoglobin (24.7%) was main composition and GD group of abnormal hemoglobin (21.9%) was second. Compared with other area of Guangdong province, the total incidence of GD group (0.108%,29/26679) in eastern Guangdong was higher than the other area (Guangzhou, Foshan, ZhangJiang) in Guangdong province (0.018%,12/66539)(P<0.05). We speculate that this is due to Hakka people and ChaoShan people had more genetic composition of Northern Han group than the people in other area of Guangdong province. According to our knowledge, it was a character that the proportion of abnormal hemoglobin of GD group in Northern Han group was higher than in Southern Han group. Therefore, proportion of abnormal hemoglobin of GD group of the eastern Guangdong people was higher than the proportion in other area of Guangdong. Hb E was the most common abnormal hemoglobin in southern Asia, which spread from south to north. It also was one of major abnormal hemoglobins in Southern China. Therefore, there was a higher proportion in the eastern Guangdon. The incidence and proportion of the K group of abnormal hemoglobin (Hb New York) of Meizhou Hakka people was significantly higher than Chaoshan people, which is consistent with previous studies. According to previous reports, Hb K, the New York originated from the Hakka people. It spread to other region in the world with the migration of Hakka people. Not consistent with the finding of previous reports, which found that Hb Q-Thailand mainly distributed in Dapu county and Fengshun county, we found that Hb Q-Thailand evenly distributed in Meizhou area in of this survey. We hypothesized that disappearing of uneven distribution of the characteristics among different regions was resulted from economic development and increased population mobility.The data of molecular epidemiological investigation of Hakka people in Meizhou area and Chaoshan people in Chaozhou area showed a genetic characterization of gene flow confluence between south China and north China. There was high proportion of GD group of abnormal hemoglobin which was a character of Northern Han. At the same time, it also showed a character of high proportion of E group and J group which was a character of Southern Han.Thalassemia and HPFHThis molecular epidemiological data of the population in eastern Guangdong was got based on the concordance between the hematological phenotype and genotype. The prevalence of thalassemia was6.12%(103/1683) in the Chaozhou population and11.5%(184/1600) in Meizhou population. The prevalence of Hakka people of Meizhou area was higher than the prevalence of Chaoshan people in Chaozhou area (P<0.05), was also higher than6.49%in Shenzhen area (P<0.05) and8.3%in HongKong area (P<0.05).The incidence of a-thalassemia was4.63%(78/1683) in Chaozhou area.75% thalassemia genotype was a-thalassemia. Inconsistent with previous report that-α3.7was the main genotype of a-thalassemia, we found that the Southeast Asian type of deletion (--SEA) was the most common genotype and-α3.7was the second. All α-thalassemia genotypes were deletion form. No any mutation thalassemia was found. The incidence of α-thalassemia was8.44%(135/1600) in Meizhou area.132cases of α-thalassemia deletion from were found, the incidence was8.25%(132/1600). The genotype was similar to Chaozhou population,--SEA was the most common genotype and-α3.7was the second. Unlike with Chaozhou population, three cases a-thalassemia mutation was found including two cases of QS and one case of CS. The genotype distribution and proportion were consistent with previous report.The incidence of p-thalassemia was1.49%(25/1683), lower than2.81%(45/1600) in Hakka people in Meizhou area. The genotype of the two populations was similar and consistent with the population in HK area and Zhongshan area. CD41-42-TCTT and IVS-II-654C>T was the most common genotype.We supposed that the inequality of thalassemia prevalence between Meizhou population and Chaozhou population was determined by the proportion of Northern Han and Southern Han. The genetic proportion of Northern Han in Chaozhou population was higher than Meizhou population. Therefore, the prevalence of thalassemia in Chaozhou population was lower than Meizhou population. The thalassemia originated from Southern Han. Therefore, the genotype was similar between them.In the survey, four cases of Hb F>5%samples were found including two cases of Vietnamese HPFH, a case of DutchI12.6kb deletion thalassemia and a cases of Belgian Gγ(Aγδβ) thalassemia. DutchI12.6kb deletion thalassemia and Belgian Gγ(Aγδβ) thalassemia were firstly reported in China. |
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