A polymorphic complex dinucleotide repeat at the telomeric D8S7 locus.

Two cosmids isolated from a flow-sorted chromosome 8 library by hybridization with pSW50 (D8S7) were screened for GT microsatellite sequences. Both contained a positive 900-bp Hind III-Xba I fragment. Sequencing revealed a complex dinucleotide repeat. Flanking oligonucleotide primers were synthesized, and the polymerase chain reaction products produced by these primers were typed within the CEPH panel of families. A two-allele polymorphism was identified that is in linkage disequilibrium with a previously described insertion-deletion polymorphism at this locus.     

Population genetics of the HRAS1 minisatellite locus.

Several years ago it was reported that rare HRAS1 VNTR alleles occurred more frequently in U.S. Caucasian cancer patients than in unaffected controls. Such an association, in theory, could be caused by undetected population heterogeneity. Also, in a study clearly relevant to this issue, it was recently reported that significant deviations from Hardy-Weinberg equilibrium exist at this locus in a sample of U.S. Caucasians. These considerations motivate our population genetic analysis of the HRAS1 locus. From published studies of the HRAS1 VNTR locus, which classified alleles into types, we found only small differences in the allele frequency distributions of samples from various European nations, although there were larger differences among ethnic groups (African American, Caucasian, and Oriental). In an analysis of variation of rare-allele frequencies among samples from four European nations, most of the variance was attributable to molecular methodology, and very samples from four European nations, most of the variance was attributable to molecular methodology, and very little of the variance was accounted for by nationality. In addition, we showed that mixture of European subpopulations should result in only minor deviations from expected genotype proportions in a Caucasian database and demonstrated that there was no significant deviation from Hardy-Weinberg equilibrium in our HRAS1 data.     

三个STR位点在哈萨克族中的遗传多态性

运用复合PCR扩增,6％变性聚丙烯酰胺凝胶电泳结合银染技术对我国新疆102位无关的哈萨克族个体进行D16S539,D7S820,D13S317的STR位点的调查,为建立新疆哈萨克族群体数据库提供资料。经统计学检验,3个位点的基因型频率分布符合Hardy-Weinberg平衡定律,结果显示3个位点的期望杂合度为：0.9439、0.9356、0.9304,累积PIC＝0.9905,DP＝0.9998,PE=9572。紫外,比较新疆哈萨克族与其他4个人群的等位片段频率,发现除与北京汉族在D7S820位点上无统计学意义外（P＞0.05）,其他均可见显著性差异（P＜0.05）。同时,在8个家系42人的调查中无一突变发现且均按孟德尔遗传规律传递。3个STR位点的联合分析在法医学应用及群体遗传学中显示了较高的价值。     

The relevance of paternity analysis in Romanian population using the D1S80 locus

At present, DNA fingerprinting for human identification and paternity testing is a necessary and usual procedure. D1S80 is one of the best known polymorphic loci showing a VNTR, and exhibiting a high heterozygosity. This genetic locus, with a Tsp 509 I polymorphism of its 5' flanking sequence (1, 9), have been successfully amplified from human genomic DNA isolated from blood. The Tsp 509 I polymorphism was detected by restriction after PCR amplification. We tested the relevance of paternity analysis using the D1S80 locus considering the allele frequency distribution characteristic for our country. Paternal and maternal bands were compared with the children's DNA patterns. Our data include a comparison between D1S80 alleles amplified from mother, child and the supposed father for three tested families. This study was the first of this type made in Romania. We concluded a good power of discrimination and exclusion for this locus. It can be used successfully in the case of subtypes with low frequencies, and this is frequent for our population because of the high heterozygosity of D1S80 subtypes in Romanian population. We recommend the D1S80 use for exclusion paternity tests in Romanian population, as a very useful molecular tool, but we also recommend a complete set of molecular markers for confirmation paternity test in the same population.     

甘肃藏族人群3个STR基因座的遗传多态性

通过D16S539、D7S820和D13S217 3个STR基因座合扩增,采用高分辨率的聚丙烯酰胺变性测序胶电泳分离,银染检测,对129名无关甘肃藏族个体进行遗传多态性研究。所有基因座经检验均符合Hardy-Weinberg平衡。在藏族人群中,观察杂合率分别是73.3%、81.4%和80.6％;PIC值分别是0.84、0.80和0.83;联合识别率是0.9999,联合亲子关系指数是7.09。结果显示该复合扩增体系在藏族人群中等位基因分布较好,适于法医个体识别及遗传学、人类学相关研究,所得数据与以前报道的汉族数据相比较,除D16S539基因座外,未发现显著差异性。     

Characterization and rapid analysis of the highly polymorphic VNTR locus D4S125 (YNZ32), closely linked to the Huntington disease gene.

The highly polymorphic VNTR locus pYNZ32 has been more extensively characterized, and its analysis converted to a rapid PCR-based format. DNA sequencing in the areas within and flanking the repeated segment allowed the design of specific amplification primers. The repeated region of pYNZ32 consists of an imperfectly duplicated 27-bp motif, 16 bases of which are more highly conserved. Allelic products from PCR amplification were resolved into nine different size classes ranging from approximately 1400 to 2200 bp. Additional polymorphism was revealed when the amplified products were analyzed by restriction enzyme digestion. Both the overall size variation and the internal sequence polymorphism were used to determine a heterozygosity value of 86% for YNZ32 in 50 unrelated individuals. The rapid analysis and improved resolution of amplified alleles on agarose gels, and the internal variability within YNZ32, increase its diagnostic utility as a VNTR and as a linkage marker for the nearby Huntington disease gene.     

Allele frequency distribution of two highly polymorphic DNA sequences in three ethnic groups and its application to the determination of paternity

The allele frequency distribution of two highly polymorphic DNA sequences has been determined in three ethnic groups (American blacks, Caucasoids, and Hispanics) from the New York metropolitan area. The two loci examined were D14S1 and the flanking region of HRAS-1. The former was analyzed in EcoRI-digested DNA and the latter in TaqI-digested DNA. Approximately 700 DNA samples from unrelated individuals were digested with each of these enzymes and hybridized with the appropriate recombinant DNA probes. The size range of the DNA fragments detected for the D14S1 polymorphism varied from 14.3 to 32.5 kilobase pairs (kbp). The number of alleles identified under the experimental conditions used in this study was more than 40. For the HRAS-1 polymorphism, we have detected 18 different alleles varying in size from 1.85 to 4.5 kbp. Although the number of alleles observed in the different ethnic groups examined was very similar, the relative frequency of them varied significantly. The results presented here can be used as the basis for the utilization of DNA RFLP for the purpose of identity, such as paternity determinations or the analysis of forensic material. As an example, we have compared the results of paternity cases analyzed by HLA typing with those obtained with these two DNA polymorphisms. The values of paternity index and power of exclusion were similar by both procedures.     

An informative MspI polymorphism detected at the D21S16 locus

Summary A new RFLP is described at the D21S16 locus formerly linked to familial Alzheimer's disease.