云南西部彝族HLA-DQA1基因构成及中华民族19个华人群体DQA1基因频率的比较分析

目的探讨云南漾濞彝族族群HLA-DQA1频率分布特征,并与华人19个群体比较。方法采用限制性片段长度多态性分析（PCR-RFLP）方法。结果DQA1*0301(31.63％)最高,*0401(1.02％)最低。卡方总体检验表明,该族群与北方六个汉人群体、满族、新加坡群体及新疆维吾尔族无显著差异(P>0.05),但有个别基因频率的显著差异;布依族、傣族、台湾群体组成复杂,与其他群体有很大显著差异（P>0.001);广东汉人与广西壮族与其他群体也有极其显著的差异;哈萨克族与维吾尔族相似;维吾尔族与部分北方汉族并无显著差异;藏族与哈萨克族、新加坡群体无显著差异。结论南方各族群DQA1的复杂构成,可能与起源的多样性或地域环境有关。漾濞彝族族群HLA-DQA1构成有北方族群特征。     

HLA-DQA1基因多态性和HBV感染结局的关联

目的 探讨人类白细胞抗原(HLA)DQA1基因多态性与乙型肝炎病毒(HBV)感染临床结局的关联.方法 临床收集慢性乙型肝炎(120例)、慢性HBV携带者(60例)、自限性HBV感染者(60例)三组病例,前两组诊断均经肝活检证实.聚合酶链反应序列特异性引物(PCR-SSP)法检测HLA-DQA1基因型,比较组间基因频率的差异.结果 (1)HLA-DQA1*0201在慢性乙型肝炎组的分布频率显著高于自限性HBV感染组(38.3% vs 5.8%,P<0.001,A=10.04,95% CI:4.48～22.48);HLA-DQA1*0102的分布频率显著低于自限性HBV感染组(9.6% vs 36.7%,P<0.001,A=0.183,95%CI:0.10～0.32).(2)HLA-DQA1*0201在慢性乙型肝炎组的分布频率显著高于慢性HBV携带者组(38.3% vs 7.5%,P<0.01,A=7.667,95% CI:3.7～15.87);HLA-DQA1*0102的分布频率显著低于慢性HBV携带者(20% vs 9.6%.P<0.01,A=0.424,95% CI:0.23～0.79).结论 HLA-DQAI基因多态性影响HBV感染临床结局,其中DQA1*0102呈保护作用,DQA1*0201可能促进HBV感染的慢性化和肝炎的发生.     

HLA-DQA1基因多态性与HBV感染结局相关

目的探讨中国汉族人群人类白细胞抗原(HLA)-DQA1基因多态性是否与乙型肝炎病毒(HBV)感染结局相关联。方法以213例HBV自限性感染者和420例慢性乙肝患者为研究对象,应用聚合酶链反应-序列特异性引物(PCR-SSP)技术进行HLA-DQA1基因分型,用EPI和SPSS软件分析DQA1多态性的分布频率及其组间差异。结果DQA1*0102在慢性乙肝组的分布频率显著低于HBV自限性感染组(15.47%比较20.42%,P<0.05),而DQA1*0201在慢性乙肝组的分布频率显著高于HBV自限性感染组(10.48%比较6.10%,P<0.05)。调整性别、年龄等混杂因素影响的非条件logistic回归分析结果显示,与HLA-DQA1其他等位基因相比,携带DQA1*0102者降低慢性乙肝发生的风险(P<0.05,OR=0.69,95%C I:0.49-0.96),而携带DQA1*0201者增加慢性乙肝发生的风险(P<0.05,OR=1.77,95%C I:1.09-2.87)。结论HLA-DQA1基因多态性可能是影响HBV感染结局的重要宿主遗传因素。     

山西汉族原发性干燥综合征与HLA-DQ基因多态性相关性的研究

目的:探讨山西汉族人群原发性干燥综合征(pSS)与HLA-DQ等位基因的相关性,从基因水平上探索pSS的发病机制。方法:应用聚合酶链反应-序列特异性引物(PCR-SSP)法对pSS患者与健康对照进行HLA-DQA1、HLA-DQB1基因的分型;采用χ2检验和Fisher’s精确检验比较两组各等位基因频率的差异。结果:(1)在100例山西汉族健康人及pSS患者中,HLA-DQA1*0501基因频率分别为12.0%和22.0%。与健康对照相比较,pSS患者中HLA-DQA1*0501基因频率显著增高(χ2=7.087,P<0.05,RR=2.068)。(2)pSS患者HLA-DQA1*0301/2等位基因频率为13.0%,显著低于健康对照组的24.5%(χ2=8.681,P<0.05,RR=0.460)。(3)pSS患者中HLA-DQB1*0201基因频率为28.5%,显著高于健康人的18.5%(χ2=5.563,P<0.05,RR=1.756)。结论:HLA-DQA1*0501和HLA-DQB1*0201等位基因可能是山西汉族pSS的易感基因,而HLA-DQA1*0301/2等位基因可能是其保护基因。     

我国部分省份(地区)汉族人群HLA-Ⅰ类基因多态性地区差异分析

目的 探讨我国部分省份(地区)汉族人群HLA-Ⅰ类经典基冈座位HLA-A、HLA-B、HLA-Cw位点的群体遗传学特点及其基因频率分布的地区差异.方法 选取1014例无关汉族拟行造血干细胞移植治疗患者及其健康家系供者的血液样本,提取基因组.DNA后,采用序列特异性引物聚合酶链式反应(PCR-SSP)分型技术进行HLA-A、HLA-B、HLA-Cw位点基因分型,分析不同地区汉族人群及不同种族间的基因频率分布特征.基于文献报道的我国不同地区汉族人群及不同种族的HLA-Ⅰ类基因频率资料,计算种群间遗传距离(D),比较不同地区汉族人群及不同种族间遗传距离差异.结果 Hard-Weinberg吻合度检验表明,本研究抽样群体适于进行遗传学统计分析.HLA-A位点共检测出14种基因型,最常见的是A*02(0.330)、A*11(0.240)、A*24(0.155)、A*33(0.075);HLA-B位点共检测出27种基因型,最常见的是B*13(0.134)、B*15(0.143)、B*40(0.133)、B*46(0.102);HLA-Cw位点共检测出13种基因型,最常见的是Cw*01(0.157)、Cw*03(0.247)、Cw*07(0.181)、Cw*08(0.106).群体汉族与其他人种间HLA-A、HLA-B基因频率差异均有统计学意义(P<0.05);除兰州汉族人群仅同南方汉族、湖南、山东、江苏、台湾汉族人群间HLA-A、HLA-B基因频率差异有统计学意义(P<0.05)外,其余各地区汉族人群间HLA-A、HLA-B基因频率差异均有统计学意义(P<0.05).各地区汉族人群间平均遗传距离D=0.164,辽宁和北方汉族人群间遗传距离(D=0.064)最小,江苏与湖南汉族人群间遗传距离(D=0.299)最大;不同地区汉族人群间遗传距离普遍小于种族间遗传距离.结论 我国不同地区汉族人群HLA-Ⅰ类基因频率分布存在显著差异,但其差异要明显小于世界不同人种间的分布差异.我国汉族人群所特有的HLA-Ⅰ类基因频率分布格局资料对区域性疾病的个性化治疗、遗传易感性及疾病防治等研究具有很好的理论及应用价值.     

中国傈僳族和怒族群体人类白细胞抗原Ⅰ类基因区Alu插入多态性研究

目的 研究中国两个隔离群体(傈僳族和怒族)人类白细胞抗原(human leukocyte antigen,HLA)Ⅰ类基因区域内5个HLA-Alu插入多态性(AluMICB、AluTF、AluHJ、AluHG和AluHF)的分布特征.方法 应用聚合酶链反应技术对中国两个隔离群体傈僳族(107人)和怒族(104人)进行HLA-Alu多态性分型.结合HLA基因分型数据,分析这两个群体中HLA-Alu插入与HLA-A、HLA-B和HLA-C基因的关系.根据HLA-Alu频率计算各群体间遗传距离,构建系统进化树.结果 AluTF和AluHF插入的频率在这两个群体间的差异有统计学意义(P＜0.05),其余位点差异无统计学意义.HLA-Alu插入与HLA的关联程度在两个群体中有差异,如AluTF*2与HLA-B* 56:01均有关联,但在傈僳族中呈强关联(74.0％),在怒族中仅存在中等程度的关联(30.7％).傈僳族和怒族群体中,HLA-Alu插入与HLA基因的不同亚型具有关联,如AluHG*2与HLA-A* 02的不同亚型存在关联.系统进化树显示中国傈僳族和怒族与我国南方群体及泰国人群聚为一支.结论 不同群体中HLA-Alu插入与HLA不同等位基因的关联程度存在差异,这种差异性为研究HLA Ⅰ类基因多样性的产生和进化、祖先单倍型的形成以及该区域内连锁不平衡和重组提供了新的线索.     

原发性肾病综合征与HLA-A、HLA-B、HLA-DRB1基因相关性的研究

目的探讨HLA-A、HLA-B、HLA-DRB1位点基因与山西汉族激素抵抗肾病综合征(SRNS)的相关性。方法用聚合酶链反应序列特异性引物法,对30例SRNS患者(成人22例,儿童8例)和45例正常对照者进行了HLA-A、HLA-B、HLA-DRB1等位基因分型,并分析了A、B、DRB1基因在各组的分布。结果SRNS患者组HLA-B*15、B*44基因频率较正常对照组增高(P<0.05);成人SRNS患者组HLA-DRB1*07、B*44基因频率较正常对照组增高(P<0.05),成人SRNS患者组HLA-DRB1*15基因频率较正常对照组降低(P<0.05);儿童SRNS患者组HLA-DRB1*10基因频率较正常对照组增高(P<0.05)。结论SRNS发病可能与HLA-B*15、B*44基因有关,成人SRNS发病可能与HLA-DRB1*07、B*44基因有关,HLA-DRB1*15对成人SRNS发病可能有保护作用,儿童SRNS发病可能与HLA-DRB1*10基因有关;HLA与SRNS的相关性不仅与人种、国家和地区有关,还可能与发病年龄有关。     

云南昆明白族、汉族、彝族儿童HLA-DQA1等位基因多态性分析

为了解昆明白族、汉族、彝族儿童HLA-DQA1等位基因多态性。采用PCR-SSP技术对昆明地区无血缘关系的3个民族儿童的HLA-DQA1等位基因进行分析。结果显示3个民族儿童HLA-DQA1基因位点上共检出14种等位基因。其中昆明白族儿童HLA-DQA1最常见的等位基因为*0601(16.67%),高频等位基因为*0103、*0102、*0303;昆明汉族儿童HLA-DQA1最常见的等位基因为*0302(26.67%),高频等位基因为*0103、*0601;昆明彝族儿童HLA-DQA1最常见的等位基因为*0601(38.57%),除*0601外没有高频等位基因,余基因频率均小余10%,同时在基因排序上3个民族也存在着差异。结果提示,昆明地区3个民族儿童HLA-DQA1基因分布既有共同特点,又有其独特性。     

新疆汉族HLA-DRB1基因多态性与再生障碍性贫血的相关性

目的探讨人类白细胞抗原(HLA)DRB1与再生障碍性贫血(AA)的相关性。方法采用序列特异性引物聚合酶链反应(PCR-SSP)DNA分型技术对43例新疆汉族AA患者(AA病例组)和200例新疆汉族人群作为健康对照者(健康对照组)进行HLA-DRB1基因分型,研究HLA-DRB1基因多态性与新疆汉族AA患者的相关性。结果 AA病例组和健康对照组的等位基因频率有相同之处,均表现为DRB1*15表达最高,同时DRB1*4、DRB1*7、DRB1*9、DRB1*12表达均较高,频率最低的均为DRB1*17;AA病例组中DRB1*8等位基因频率(13.73%)显著高于对照组(6.99%),差异有统计学意义(OR=2.202,P0.05);AA病例组DRB1*12、DRB1*14等位基因频率低于对照组,差异无统计学意义。其中AA病例组女性等位基因DRB1*12(5.41%vs 10.00%,OR=0.2079,P0.05)和AA病例组男性DRB1*14等位基因频率(2.11%)显著低于对照组(7.53%),差异有统计学意义(OR=0.1403,P0.05);AA病例组女性DRB1*15等位基因频率(27.45%)显著高于对照组(14.56%),差异有统计学意义(OR=2.433,P0.05)。结论 DRB1*08可能是AA患者的易感基因;DRB1*12可能是女性AA患者拮抗基因;DRB1*14可能是男性AA患者的拮抗基因;DRB1*15可能是女性AA患者的易感基因。     

云南西部彝族HLA—DQA1基因构成及中华民族19个华人群体DQA1基因频率的比较

目的：探讨云南漾濞彝族族群ＨＬＡ－ＤＱＡ１频率分布特征，并与华人１９个群体比较。方法：采用限制性片段长度多态性分析（ＰＣＲ－ＲＦＬＰ）方法。结果：ＤＱＡ１＊０３０１（３１．６３％）最高，＊０４０１（１．０２％）最低，。卡方总体验表明，该族群与北方六个汉人群体、满族、新加坡群体及新疆维吾尔族无显著差异（Ｐ〉０．０５），但有个别基因频率的显著差异；布依族、傣族、台湾群体组成复杂，与其他群体有很大显著差异（Ｐ〉０．００１）；广东汉人与广西壮族与其他群体也有极其显著的差异；哈萨克族与维吾尔族相似；维吾尔族与部分北方汉族并无显著差异；藏族与哈萨克族、新加坡群体无显著差异。结论：南方各族群ＤＱＡ１的复杂构成，可能与起源的多样性或地域环境有关。漾濞彝族族群ＨＬＡ－ＤＱＡ１构成有北方族群特征。     

Population genetics of coagulation factor XIIIB in three ethnic groups of Singapore.

The distribution of plasma coagulation factor XXIIB polymorphism was determined by PAG isoelectric focusing and immunoblotting in a group of 670 subjects comprising 375 Chinese, 110 Malays and 185 Indians. The frequencies of FXIIIB*1, FXIIIB*2, and FXIIIB*3 were found to be 0.27, 0.03 and 0.70 in the Chinese; 0.33, 0.05 and 0.64 in the Malays and 0.58, 0.08 and 0.33 in the Indians. The phenotypic distribution of FXIIIB alleles was at Hardy-Weinberg equilibrium in all three populations. A two-dimensional principal-components analysis on the basis of three common alleles at the FXIIIB locus among 19 populations, so far studied, clearly differentiates the Negroid, Mongoloid and Caucasoid populations into three major groups with the exception of Amerindians (Minnesota) and US Blacks showing some Caucasoid influence.     

Allele and haplotype frequencies at human leukocyte antigen class I and II genes in Venezuela's population

Population studies represent an integral part and link in understanding the complex chain of host-pathogen interactions, disease pathogenesis, and MHC gene polymorphisms. Genes of Mongoloid, Caucasoid, and Negroid populations have created a distinctive HLA genetic profile in the Venezuelan population. Our objective was to determine the predominant HLA class I and II alleles and haplotype frequencies in the hybrid population of Venezuela. The study population consisted of 486 healthy unrelated native Venezuelans and 180 families. We examined the frequency of HLA A-B-C, HLA-DQ and HLA-DR genes by polymerase chain reaction and subsequent hybridization with sequence-specific oligonucleotide probes. Phenotypic, allelic and haplotype frequencies were estimated by direct counting and using the maximum-likelihood method. The predominant HLA class I alleles were A*02, A*24, A*68, B*35, B*44, B*51, B*07, B*15 and Cw*07. Regarding HLA class II, the most frequent alleles were DQB1*03 and DRB1*04, DRB1*15, DRB1*13, DRB1*07. The prevailing haplotype was HLA-A*02B*35 DQB1*03 DRB1*04. Some of these alleles and haplotype frequencies were predominantly present in Amerindians (A*02, A*24, B*35, Cw*07, DRB1*04, A*24 B*35). Previous reports have shown high incidence of A*02, B*44, B*51, DRB1*15, DRB1*13, DRB1*07 alleles in several European populations and A*68, B*07, B*15 alleles in African Americans, which could have contributed to the ethnic admixture of the Venezuelan population. We conclude that our results provide strong evidence that Venezuela's population represents an admixture of the primitive Mongoloid Aborigines, Caucasoid Europeans and Western African Negroid migrants.     

HLA in the Azores Archipelago: possible presence of Mongoloid genes

The HLA profile of the Azoreans has been compared with those of other world populations in order to provide additional information regarding the history of their origins. The allele frequencies, genetic distances between populations, correspondence analyses and most frequent haplotypes were calculated. Our results indicate that the Azorean population most likely contains an admixture of high-frequency Caucasoid, Mongoloid and, to a lesser degree, Negroid HLA genes. The middle Atlantic Azores Archipelago was officially colonized by the Portuguese after 1439 and historical records are concordant with the existence of Caucasoid and Negroid population. However, Mongoloid genes were not suspected, but the Oriental HLA haplotypes A24-B44-DR6-DQ1, A29-B21-DR7-DQ2 and A2-B50-DR7-DQ2 are the fourth, fifth and sixth most frequent ones in Azores. A correspondence analysis shows that the Azorean population is equidistant from Asian and European populations and genetic distances are in some cases closer to the Asian than to European ethnic groups, and never are significantly different; also, B*2707 subtype is found in Asians and Azoreans (but not in Europeans) and the same Machado-Joseph Disease founder haplotypes (Chr 14) are found in both Japanese and Azoreans. It is proposed that a Mongoloid population exists in Azores; whether, the arrival occurred prior to discovery is undetermined.     

Apolipoprotein B 3'-VNTR polymorphism in Eastern European populations

Apolipoprotein B 3' (3' ApoB) minisatellite polymorphism was studied in healthy unrelated individuals from the Russian Federation and the Republic of Belarus, in 10 populations from five ethnic groups: Russians, Byelorussians, Adygeis, Kalmyks and Yakuts. The analysis was carried out using PCR and electrophoresis followed by silver staining. Overall, 25 alleles of the 3' ApoB minisatellite, ranging from 25 to 55 repeats, were detected. Heterozygosity indices were high and varied from 0.73 to 0.84. The distributions of alleles of this minisatellite in the Caucasoid populations (Russians, Byelorussians and Adygeis) had a bimodal character, whereas that for Mongoloid populations (Kalmyks and Yakuts) had a unimodal distribution. Nei's genetic distances between the populations studied and some reference populations of Europe and Asia were estimated. Despite their allele distribution homogeneity, different East Slavonic ethnic groups were clearly resolved by multidimensional analyses. The East Slavonic and Adygei populations revealed a high similarity with European Caucasoids. The Mongoloid populations (Kalmyks and Yakuts) were considerably different from those of the European Caucasoid populations, but were similar to other Asian Mongoloid populations. The results demonstrate the variability of 3' ApoB minisatellite polymorphism not only in distant populations but also, to a certain extent, in genetically relative ones.     

Study of HLA antigens in a population of Mali (West Africa)

Eighty-two healthy individuals have been typed for HLA-A, B, C, antigens, and 49 of them also for HLA DR alleles. They were a sample representative of 11 of the 14 Malian ethnic groups living in the area of Bamako (Mali). Phenotypic frequencies have been compared to those of other Negroid and Caucasoid reference populations. As expected, in Negroids the increased frequency of HLA A23, A28, A30, and ATh was confirmed in the present series. Additionally, a significantly increased frequency of HLA B5 (B51 and Bw52) was noted--already observed in some but not all Negroid populations. Conversely, a decreased frequency--compared with that usually found in Negroid population--was observed for the alleles Bw42, Bw58, Cw6, and DRw6. Our results underline the originality of the Malian population among Western Africans.     

Genetic variability of Apolipoprotein E in different populations from Venezuela

The genetic variation at the Apolipoprotein E locus (APOE) is an important determinant of plasma lipids and has been implicated in various human pathological conditions. The objective of the present study was to estimate the distribution of APOE alleles in five Venezuelan communities: two Amerindian tribes (Bari and Yucpa), one Negroid population from Curiepe, one Caucasoid population from Colonia Tovar and the Mestizo urban population living in Caracas. The APOE*3 allele was the most common allele in all populations studied. However, a significant increase in the APOE*2 allele frequency in the Mestizo (18.96%) and Negroid (16.25%) populations was found. Similar to results reported in other Native American populations we have found that the APOE*2 allele is completely absent in the Bari and Yucpa Amerindians. Frequencies found in the Colonia Tovar population are in agreement with those reported in the population of Germany, indicating a high degree of relatedness. The results support the notion that the distribution of the APOE alleles shows ethnic variability.     

Survey of seven plasma protein polymorphisms in the Amhara and Oromo populations of Ethiopia

The Ethiopian population is very difficult to specify due to a very high degree of intermixing among different peoples. The two groups of the present study, the Amhara and Oromo, constitute 38% and 35% of the population, respectively. In order to investigate the genetic composition of the Amhara and Oromo, genetic polymorphisms of seven plasma proteins (F13A, F13B, ORM1, AHSG, C6, C7, and APOC2), already identified as useful anthropological markers, were studied. No statistically relevant differences were found between the two groups for all of the systems examined. ORM1 and F13A showed frequencies in the range observed in other populations of Caucasoid and Negroid origin. F13B, AHSG, and C6 displayed gene frequencies and a number of variant alleles that seem particular to these two groups. No variation was observed for C7 and APOC2. Correspondence and distance analyses were used to interpret and compare the gene frequencies of the Amhara and Oromo with those of other related populations. These methods locate Ethiopians in an intermediate position between African Blacks and a group of Caucasoid populations, confirming cultural and historical data. © 1994 Wiley-Liss, Inc.     

Genetic structure and affinity among eight ethnic populations of Eastern India: based on 22 polymorphic DNA loci.

The nature and extent of genetic variation at 22 polymorphic DNA loci, belonging to three distinct classes, especially, 12 STR loci (D3S1358, vWA, FGA, D5S818, D13S317, D7S820, D8S1179, D21S11, D18S51, HPRTB, F13B, LPL), four VNTR loci (D1S7, D4S139, D5S110, D17S79), and six coding loci (HLDQA1, LDLR, GYPA, HBGG, D7S8, GC) were investigated among eight population groups of West Bengal and Manipur regions of India. Of these, two groups from West Bengal belong to Caucasoid and six (one in WB and five in Manipur) belong to Mongoloid stock. Both STR and the expressed loci show wide diversity among the eight populations. For example, Manipur Muslims show differences in allele frequency when compared to four other regional populations. Similarly, Garo, one of the Mongoloid populations of West Bengal, differ in allele frequency from their counterparts in the Manipur region. Departure from Hardy-Weinberg expectations was observed at certain loci in a few populations (e.g., D21S1137 in Kayastha and Brahmin, HUM F13B in Meitei). Heterozygosity values were higher for Caucasoid than Mongoloid groups. The overall gene differentiation (GST) for STR loci is higher (5.3%) than for those at the expressed region (4.6%). The clustering pattern of the eight populations differs with respect to different classes of genetic markers used. The dendrograms based on six coding loci (HLDQA1, LDLR, GYPA, HBGG, D7S8, GC) differs from those based on STR and VNTR markers. Caucasoid and Mongoloid groups form different clusters and Manipur Muslims are distinct from others. The clustering pattern corresponded with the spatial and ethnic affiliations of the populations. Using different classes of DNA loci at the coding and noncoding region will help to better understand the influence of population structure variables on the genetic structure of populations.     

洛阳地区汉族HLA—DRB1^＊04等位基因的PCR—SSO分型

对河南洛阳地区汉族进行了ＨＬＡ－ＤＲＢ１＊０４等位基因的ＰＣＲ－ＳＳＯ分型，采用第１２届国示组织相容性专题讨论会推荐的引物和序列特异性寡核苷酸探针，可检测１７个ＤＲＢ１＊０４组特异性等位基因，在１１６份无血缘关系健康人ＤＮＡ村洒中有１６份为ＤＲＢ１＊０４，其中１份为纯合，ＤＲＢ１＊０４的基因频率为０．０７１５。ＤＲＢ１＊０４等位基因分布于５个不同的型别，分别是ＤＲＢ１＊０４０１、０４０３、０４０４     

Genetic heterogeneity in northeastern India: Reflection of Tribe–Caste continuum in the genetic structure

We critically examined the gene frequency data for 11 genetic markers commonly available in the literature for 22 populations of northeastern India in the light of their geographic, linguistic, and ethnic affiliations. The markers investigated were three blood groups (A₁A₂BO, MNS, and Rh), four serum proteins (KM, Gc, Hp, and Tf), and four enzyme systems (AP, AK, EsD, and Hb). The neighbor‐joining tree and multidimensional scaling of the distance matrix suggest relatively high genetic differentiation among the Mongoloid groups, with probably diverse origins when compared to the Caucasoid Indo‐European populations, which had probably come from relatively more homogeneous backgrounds. Broadly speaking, the pattern of population affinities conforms to the ethno‐historic, linguistic, and geographic backgrounds. An interesting and important feature that emerges from this analysis is the reflection of the effect of the sociological process of a Tribe–Caste continuum on genetic structure. While on one end we have the cluster of Caucasoid caste populations, the other end consists of Mongoloid tribal groups. In between are the populations which were originally tribes but now have become semi‐Hinduized caste groups, viz., Rajbanshi, Chutiya, and Ahom. These groups have currently assumed caste status and speak Indo‐European languages. Therefore, one may infer that what appears to be a purely sociological phenomenon of a Tribe–Caste continuum may well reflect in their genetic structure. Am. J. Hum. Biol. 16:334–345, 2004. © 2004 Wiley‐Liss, Inc.