【作者】 温有锋；

【导师】 席焕久；

【作者基本信息】 中国医科大学 ， 人体解剖与组织胚胎学， 2007， 博士

【摘要】 西藏藏族起源初探目的获得西藏藏族mtDNA和Y染色体DNA多态性信息，从母系遗传和父系遗传角度探索藏族的起源，同时也为藏族人群个体识别提供参考资料；评价藏族青少年的体型，获得藏族青少年的体型特点及发育规律，比较藏族与其他群体体型的差异，从体型角度分析藏族的起源；调查藏族的皮纹参数，丰富藏族的肤纹学资料，并从皮纹角度探索藏族的起源。方法采用分层整群抽样的方法，从西藏9所院校中抽取父母为藏族，本人始终在西藏生活，彼此间无亲缘关系，经体检健康的青少年为研究对象，年龄范围7～20岁，共调查2592人。在知情同意原则的基础上，分别进行问卷调查、体质测量(身高、体重、手长等12项体质指标)、掌指纹拓印、血样采集。采用Heath-Carter体型法计算并判定体型；观察指纹纹型、嵴线计数、掌褶纹类型、atd角等11项掌指纹参数；采用PCR、琼脂糖电泳分型法分析mtDNA V区和DYS287位点多态性；对mtDNA高变区I采用PCR扩增，然后测序，测序结果与剑桥标准序列比较，用EBI软件中ClustalW数据包进行排序，确定变异位点和变异类型，使用MEGA 2.1软件构建系统进化树，通过Arlequin2.0中的AMOVA程序进行分析拉萨、那曲藏族的遗传结构。结果1、拉萨、那曲两地区藏族mtDNA HVR I区序列与剑桥标准序列比较后，分别检测到31和34种单倍型，突变部位均有51处，碱基转换分别为141个和128个，分别占碱基突变的89.81％和88.89％，突变的热点部位分别出现在np16223和np16362，其突变频率分别为90.32％(npl6223)、64.51％(npl6362)和83.33％(np16223)、58.33％(np16362)，两地区人群的核苷酸多样性分别为0.016058±0.008740(拉萨)和0.016084±0.008795(那曲)；拉萨、那曲地区藏族在np 16180～16194区域形成的C重复单倍型分别为4种和9种。拉萨、那曲藏族群体的Mismatch分布曲线呈单峰，Tau值分别为6.331和5.590，进而推算出拉萨、那曲群体扩张时间分别发生在距今约5.3和4.7万年前。拉萨、那曲藏族群体间的差异占总变异的0.96％(P=0.1212)。系统进化树显示，拉萨、那曲藏族首先聚为一类，然后再与西安汉族、蒙古人和其他东亚人群聚为一类，各个人群最后与非洲人会聚成一大类。拉萨、那曲的基因变异度(h)分别为0.9862和0.9961；偶合概率分别为0.0466和0.0316。2、mtDNA V区检测到标准型和9bp缺失两种基因型，缺失型的频率为5.52％(其中拉萨市为4.88％，那曲地区为6.17％)。拉萨市和那曲地区两地藏族群体间mtDNAV区9bp缺失频率不具有显著性差异(X~2=0.131，P＞0.05)。3、DYS287位点共检测到yAp~+和YAP~-两种基因型，YAP~+频率为54.28％(其中拉萨市为41.46％，那曲地区为62.50％)，拉萨市和那曲地区两地藏族群体间DYS287位点yAp~+频率具有显著性差异(X~2=4.46，P＜0.05)。4、藏族青少年的平均体型男性为偏中胚层的外胚层型(2.5-3.1-3.8)，女性为外胚层-内胚层均衡型(3.7-2.6-3.4)；男性的体型以外胚层系体型为主(58.52％)，女性体型以内胚层系和(39.52％)外胚层系为主(38.81％)；随着年龄的增长，藏族青少年的体型发展有一定的规律，男性由中胚层-外胚层均衡型经偏中胚层的外胚层型又发展回中胚层-外胚层均衡型，女性由中胚层-外胚层均衡型经历均衡的外胚层型发展为均衡的内胚层型。5、藏族指纹以斗型纹为主(58.99％)，其次为箕型纹(38.25％)，弓形纹出现频率最低(2.76.％)，1手5指组合格局以5W出现频率最高(22.44％)；总指嵴线计数为139.01(其中男性为144.75，女性为133.87)；总指嵴线计数、ab嵴线计数、ad嵴线计数、td嵴线计数均表现男性大于女性，且总指嵴线计数、td嵴线计数男女性间比较有显著性差异(P＜0.01)；atd角在男性为42.95°，女性为43.28°，在男性均表现为右侧大于左侧，而在女性恰恰相反；掌褶纹中以普通型最多见(81.15％)，悉尼型最少(1.31％)，通贯手的出现频率为2.03％。藏族的皮纹密度随年龄的升高而减小，女性皮纹密度大于男性，且差异有显著性(P＜0.05)。结论1、西藏藏族mtDNAHVRⅠ具有较高的核苷酸多态性，与东亚琉球人和台湾汉族非常接近，同时，系统进化树也显示藏族与蒙古人、东亚人具有较近的亲缘关系；拉萨、那曲藏族之间的基因多态性不具有显著性差异；本研究为藏族mtDNAD-loop区在法医学领域中的应用提供了基础数据，并进一步证实了mtDNA在法医学领域中可能具有很高的应用价值。2、藏族mtDNA V区9bp缺失的频率与蒙古族等北方起源的民族接近，验证了藏族属于我国北方族群的观点。3、藏族DYS287位点YAP~+频率很高，其中在牧区(那曲)保持最高的频率(62.5％)，从而证明那曲是一个隔离群，是探索藏族起源的最佳人群。4、藏族男性青少年身体的线性程度高、外形上比较瘦削、肌肉较发达；藏族女性青少年较男性身体的脂肪含量多、线性程度相对较高；体型的地区差异(城区与牧区)，主要发生在生长发育较快的时期，之后两个地区的体型较相似，但城区的营养状态好于牧区；与汉族等八个群体的青少年相比藏族青少年身体脂肪含量较少，骨骼、肌肉不甚发达，体型较纤细。5、藏族的体型与汉族很相似，与同属游牧民族的蒙古族和达斡尔族较相似，而与白色人种(芬兰、匈牙利)和黑色人种(尼日利亚)差异很大。从体型角度推测，藏族和汉族可能有共同的祖先。6、随着年龄的增长，藏族青少年的皮纹密度逐渐减小，ab皮纹密度、ad皮纹密度均是女性大于男性，藏族的皮纹密度大于同年龄组汉族的皮纹密度。通过对藏族等57个群体肤纹学参数的聚类分析推断藏族与汉族和氐羌氏族的亲缘关系较近，而与印度人和孟加拉人的亲缘关系较远。更多还原

【Abstract】 Preliminary Study on the Origin of Tibetan Ethnic Population in TibetObjectiveThe purpose of this paper was to obtain the polymorphism information of mitochondria DNA and Y chromosome DNA on Tibetan ethnic population in Tibet for exploring the origin of Tibetan ethnic population with maternal and paternal inheritance, to provide the reference data for individual identification of Tibetan ethnic population, and to evaluate the somatotype of the Tibetan adolescent for obtaining the character and developmental regularity of the Tibetan ethnic population, to compare the Tibetan somatotype with the other groups’ in order to analyzing the origin of Tibetan ethnic population with somatotype, and to investigate the parameter of dermatoglyphics on Tibetan ethnic population for accumulating the dermatoglyphical data of Tibetan ethnic population and exploring the origin of Tibetan ethnic population with dermatoglyphicsMethodsThe 2592 samples who were healthy and lived in Tibet all the time were selected from unrelated adolescents aged from 7 to 20 years old in nine schools of Tibet with stratified cluster sampling method. 12 anthropometric measurement indexes including height, weight, hand length and so on were measured. The somatotype were evaluated by Heath-Carter somatotyping method. 11 dermatoglyphical parameters including the type of finger and palm, finger ridge count, atd angle and so on were assessed, mtDNA region Vand DYS287 locus were amplified and typed by gelose electrophoresis. The polymorphism of mtDNA Hypervariable regionⅠwas amplified by polymerase chain reaction, then sequenced on ABI-3100Avant. Compared to Combridge reference sequence, the sequences were sorted by ClustalW database in EBI software. The position and type of variation were found and arranged. Phylogenetic tree was constructed by MEGA2.1 software and the genetic structure of Tibetan ethnic population in Lhasa and Naqu was analysed by AMOVA program in Arlequin2.0. Results1. Compared to Combridge reference sequence, the sequence of Lhasa and Naqu were detected 31and 36 haplotypes, 51 loci, 141and 128 base conversion (89.81% and 88.89% total mutation), the positions of mutational hot spot were np16223 and np16362, the frequency of mutations in Lhasa and Naqu was 90.32%, 64.51% and 83.33%, 58.33% respectively. The nucleotide diversity in Lhasa and Naqu was 0.016058±0.008740, 0.016084±0.008795 respectively. The poly-C haplotype of Lhasa and Naqu in np16180-np16194 was 4 and 9 respectively. The mismatch distribution curve of Lhasa and Naqu were single peak, the Tau values was 6.331 and 5.590 respectively. The expending time of Lhasa Tibetan ethnic population was 53 thousands years ago and Naqu Tibetan ethnic population was 42 thousands years ago. The variation between Lhasa and Naqu population is 0.96 % (P=0.1212). Phylogenetic tree shows Lhasa and Naqu population first clustering, then Han nationality of Xi’an, Mongolian and other East-Asian group clustering, finally, the African and all population clustering. The genetic diversity of Lhasa and Naqu is 0.9862 and 0.9961, respectively. The genetic identity of Lhasa and Naqu is 0.0466 and 0.0316, respectively.2. We detected two gene types that was normal type and the type of 9bp deletion in mtDNA region V. The frequency of 9bp deletion was 4.88% in Lhasa group, 6.17% in Naqu group and the total frequency of 9bp deletion was 5.52%. There was no significant difference between Lhasa group and Naqu group in mtDNA region V 9bp deletion(X~2=0.131, P＞0.05).3. We observed two gene types: YAP~+ and YAP in DYS287 locus. The frequency of YAP~+ 54.28%, of the total was 4.46%, 62.50 in Lhasa and Naqu respectively. There was no significant difference between Lhasa group and Naqu group in DYS287 locus YAP~+(X~2=4.46, P＜0.05).4. The average somatotype of Tibetan adolescents in male is Mesomorphic Ectomorphy (2.40-3.29-3.72); in female, the average somatotype is central (3.65-2.87-3.32). The somatotype growth of Tibetan adolescents has special regularities: with age increasing the somatotypes develop from mesomorph-ectomorphy, mesomorphtic ctomorphy to mesomorph-ectomorphy in male, however, in female from Ectomorph-Endomorphy, Balanced Ectomorphy, Ectomorph-Endomorphy Ectomorphic Endomorphy to Balanced Endomorphy.5. In Tibetan ethnic population, whole(58.99%) was the dominant fingerprint type, Loop(38.25%) was secondly, arch(2.76. %) was the lowest. We observed the highest frequency on the combination pattern of five finger in one hand was 5W. Total finger ridge count was 144.75 in male, in female was 133.87 and the mean was 139.01. Total finger ridge count, ab finger ridge count, ad finger ridge count and td finger ridge count all showed man more than female, and significantly in total finger ridge count and td finger ridge count. Atd angle was 42.95°and 43.28°respectively in male and female. Atd angle showed right more than left in male, in female conversely. In palm crease, popular type (81.15%) was dominant, Sydney type (1.31%) was lowest and the frequency of simian line was 2.03%. The density of dermatoglyphics in Tibetan adolescents descent with age increasing, and differed in sex(P×0.05), man’s more than female’s.Conclusions1. Nucleotide diversity of Tibetan mtDNA is high, is closer to East Asian and Mongolian, and phylogenetic tree show the relation between Tibetan and East Asian and Mongolian is closer; the significant difference was not found between Lhasa and Naqu population. The study provides basic datas of Tibetan mtDNA D-loop for forensic medicine, these results suggest that sequence Polymorphism of mtDNA control region would be very useful in forensic practice as a marker for individual identification.2. The frequency of mtDNA regionⅤ9bp deletion in Tibetan ethnic population is similar to the races which origin from northen like Mongolia nationality, so it confirms that Tibetan ethnic population belongs to northern group in our country.3. Tibetan YAP~+ frequency of DYS287 locus is higher, and highest in Naqu(62.5%), so we conclude that the Tibetan ethnic population in Naqu is a isolate and they are the optimal samples to explore the origin of Tibetan ethnic population.4. The somatotypes of Tibetan adolescent in male are more slender and muscles are stronger, the shape is more slender and body fat is more in female. During the period of growing and developing quickly, the difference of the somatotypes of Tibetan adolescents between city(Lhasa) and pasture (Naqu) were significant and the nutritional status of city is prior to pasture. Compared with the other eight groups (like Han nationality and so on), body fat is less and skeleton and muscles are not very strong in Tibetan adolescents.5. The somatotype of Tibetan ethnic population is the most closed to Han nationality, and similar to nomads like Mongolian and dsfasfs, but differs from nordic (Finland, Hungary) and melanian (Nigeria). So we can conclude from somatotype that there are the common ancestor Tibetan ethnic population and Han nationality.6. The density of dermatoglyphics of Tibetan adolescents descent with age increasing, and differed in sex. Ab density of dermatoglyphics and ad density of dermatoglyphics show man more than female. The density of dermatoglyphics of Tibetan adolescents is more than Han nationality’s. It is concluded that Tibetan ethnic population is closd to Han nationality and Diqiangshi nationality, however farther to Indian and Bengal through clustering 57 groups like Tibetan ethnic population.更多还原