Mutations of 15 short tandem repeat loci in Chinese population.

OBJECTIVE: To explore the mutations of 15 short tandem repeat (STR) loci in PlowerPlex16 System which are world-widely used in parentage testing. METHODS: Mutations of 15 STR loci in PlowerPlex16 System were investigated in 1921 parentage testing cases from Chinese population. RESULTS: In 1921 parentage cases, seventy cases (3.644%) were found to have mutations. Among these were one case with double mutations (D21S11 and PentaD) and another case with two different mutations (D7S820 and D16S539) in two children. The total number of mutated STR loci observed was 72 over 3764 meiosis with a mutation rate of 0.128% +/- 0.1104% x 10(-3). The highest mutation rate was 0.292% at vWA and D21S11. No mutation was observed at TH01 or at TPOX. The mutated alleles coming from father were five times more than those from mother. The majority (98.611%) of mutated alleles were the results of one-step mutation. The ratio of one-step gain versus loss was 1.826:1. There was only one multiple-step mutation with a double-repeat gain observed at PentaD locus. In the PlowerPlex16 System, nine loci, namely D8S1179, Penta D, D13S317, D16S539, D7S820, D5S818, D3S1358, TH01 and TPOX, have lower mutation rates and are more suitable for parentage testing. CONCLUSION: Mutation of STR is relatively common and often makes parentage testing more complicated. Selecting stable STR locus with low mutation rate is more important in parentage testing.

Rapid detection of six common Chinese G6PD mutations by MALDI-TOF MS.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked hereditary enzymopathy. We describe here the techniques based on matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and multiprimer extension (multi-PEX) to detect the most common Chinese G6PD mutations, which are the single-point mutations G-->T at nt 1376, G-->A at nt 1388, A-->G at nt 95, G-->T at nt 392, C-->T at nt 1024, and C-->T at nt 1311. Fifteen samples were genotyped using this method coupled with direct sequencing, after identification of G6PD mutations by ARMS. In this study, we identified a mutation G-->T at nt 1376, which had been G-->A at nt 1388 using ARMS, while the result of sequencing corresponds with ours. This indicates the reliability of this method. Furthermore, since it can scan six common Chinese G6PD mutations simultaneously in one mass spectrum, this approach could be used to fast diagnose these G6PD mutations accurately in large-scale analysis.

[The characteristics of polymorphism and gene structure of DYF155S1 locus in Y-specific minisatellite from Chinese Uygur population].

The study is to reveal the diversity and gene structure of 5' and 3' end of DYF155S1 locus in Y-chromosome minisatellite among Chinese Uygur population. Fluorescent MVR-PCR(minisatellite variant repeat by PCR), Amp-FLP(Amplified fragment length polymorphism) and DNA sequencing methods were used respectively to detect 106 unrelated males among Chinese Uygur population. The polymorphisms of DYF155S1 locus could be revealed in three aspects: (1) polymorphic length: the sizes of amplified fragments ranged from 1405 to 2505 bp. There are 37 types found among the 106 unrelated males. (2) polymorphism at 5' end of DYF155S1 locus, 68 types found among the 106 unrelated males. (3) polymorphism at 3' end of DYF155S1 locus, 23 types found among the 106 unrelated males. In combination of these three aspects of polymorphism, none of the 106 unrelated males tested had the same allele, and the gene diversity (h) was over 0.9999. Seven and two types of modular structure were founded in the 5' and 3' end of DYF155S1 locus, respectively, by DNA sequencing. The alleles at DYF155S2 locus showed yes/no dimorphism and the rate of deletion was 4.7%. The polymorphisms of DYF155S1 locus were fully revealed by using combination of MVR-PCR, Amp-FLP and DNA sequencing methods, and we suggested the nomenclature for alleles of MVR loci. These methods are useful tools and provide basic data for the study of human genetics and forensic medicine.

[Sequence variation of D12S391 and D11S554 loci in Guangzhou han population].

To study the core sequence of the hypervariable short tandom repeats, we sequenced the alleles of D12S391 and D11S554 loci which show high mutation rate in Guangzhou Han population. The D12S391 locus has the basic sequence structure (AGAT)8-17 (AGAC)6-10 (AGAT)0-1. The smaller alleles (15-18) at D12S391 locus have variation limited to the number of the first repeat (AGAT), whereas the larger alleles (19-27) have more complex variation in the number not only of the first repeat but also of the other two repeats (AGAC) and (AGAT). Four new alleles named 22", 23", 24"' and 27 respectively were found. The D11S554 locus has more complex core sequence classified into five sequence types. Three of them have the same basic sequence structure (AAAGG) (AAAG)4 (AAAGG)2-3 (AAAG)13-19. In the larger alleles (219-249), there are four and five nucleotide repeats. Some of the larger alleles(219-249) have one base variation, bases insert or deletion. The two loci all have sequence heterogeneity. Our results indicated that the two loci D12S391 and D11S554 belong to complex repeats and this adds difficulty to their correctly typing. It is essential to construct allelic ladder in each population.

[DNA analysis of a 500 year mummy sample].

OBJECTIVE: To accumulate experience for dated forensic matter analysis, for example, Mummy. METHODS: DNA are extracted by methods of phenol-chloroform and are purified by Wizard DNA clean-up system. The STRs locus are ampolification with Promega Powerplus 16 system. The mtDNA hypervariable region 1 (HV1) is amplificated by '3 pair primers'. The products were sequenced with 377 DNA sequencer. RESULTS: The STRs locus very distinctness and mtDNA sequence is correct. CONCLUSION: It is a valuable method for special forensic matters.

[Studying the polymorphism at DYF155S1 locus in Chinese Han population by MVR-PCR marked with fluorescence].

The simple and useful genotyping methods of DYF155S1 locus by silver staining and fluorescence detection have been established. The blood samples from 155 unrelated males in Chinese Han population were typed by these two methods respectively and the same results were obtained. Among the 155 samples 66 alleles were found, out of them 38 were observed once only. The most frequent alleles named 18 or 22, which frequency was 0.065, the size of their first DNA fragments was 180 bp and the number of fragments was 16 or 17. The gene diversity (h) was 0.9789. Out of the 155 samples, 25 samples had one or two bands lost (null repeat) among the successive bands. It was demonstrated by sequencing that the position of the lost bands corresponded to type 3 repeats. Our results indicated that the method, which revealed the 5' end diversity of DYF155S1 locus, was a technique that could obtain the most Y-specific polymorphic information only by one PCR reaction. The allele frequencies of DYF155S1 locus in Chinese Han population provided the basic data for the study of population genetics and forensic practices.