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Structure of new mutations in 2 STR systems.

Isolated father/child mismatches in cases with a high probability of paternity (W > 99.9%) have been investigated using short tandem repeat (STR) systems. According to the high probability of paternity new mutations could be assumed in these cases. A new mutation could be observed in 3 cases using the STR system HumACTBP2. Two of these cases showed a deletion and 1 case an insertion of 1 repeat (AAAG-motif) which could be verified by sequencing. In another paternity case a new mutation--1-repeat insertion (TCTA-motif)--in the HumVWA system was detected and verified by sequencing. These findings led to a new mutation rate of 0.7% (n = 453 meioses) for HumACTBP2 and 0.2% for HumVWA (n = 484 meioses).

Adult↗

Population genetics of short tandem repeat (STR) loci.

To investigate the population genetics of short tandem repeat (STR) polymorphisms in human populations, we have studied the allele frequency distributions of four STR loci (HUMTH01, HUMVWA31, HUMF13A1 and HUMFES) in 16 different population surveys which can be categorised within three broadly defined ethnic groups: Caucasian, Asian (Indian subcontinent), and African (Afro-Caribbean and US black). We have observed that allele frequency distributions of populations within ethnic groups are similar; consequently, genetic distances are an order of magnitude lower than between ethnic groups. Inbreeding coefficients (F-statistics) and calculations of the number of mean heterozygous loci per individual, along with estimates of variance, did not suggest that the populations were substructured. This included a study of an immigrant Asian population known to comprise at least three different sub-groups. Finally, an indication of the discriminating power is given by calculation of likelihood ratios (LR) of each individual tested across all four loci. Approximately 70% of Caucasians give an LR of greater than 10,000; the test is even more discriminating in Afro-Caribbeans--approximately 90% of tests are greater than 10,000.

Alleles↗

Frequencies for five short tandem repeat (STR) systems in a population from north Poland.

A population study of unrelated individuals from North Poland (Gdansk area) was carried out to investigate the allele distributions of the five STR systems HUMCD4, HUMFES/FPS, HUMVWA31, HUMTH01 and ACTBP2. PCR products were separated on horizontal non-denaturing polyacrylamide gels followed by silver staining. For all STR systems analysed the distribution of observed phenotypes did not deviate from Hardy-Weinberg equilibrium. A comparison of allele distributions between Polish and other European Caucasian population samples is presented.

Alleles↗

Gender-specific associations between MICA-STR and nasopharyngeal carcinoma in a southern Chinese Han population.

Previous studies have identified several HLA-B specificities that are associated with nasopharyngeal carcinoma (NPC) in populations of Chinese descent, in particular HLA-B35, -B38, -B46, and -B58. Perhaps except for HLA-B46, other associations cannot be simply accounted for by the linkage disequilibrium between HLA-A and B loci. The human major histocompatibility complex (MHC) class I chain-related gene A (MICA) maps 46 kb centromeric to HLA-B and is highly polymorphic; it encodes a stress-inducible protein which functions as a ligand for the NKG2D/DAP10 complex to activate natural killer (NK) cells, gammadelta T cells, and CD8(+) T cells. We postulated MICA gene as a susceptibility factor for nasopharyngeal carcinoma, an Epstein-Barr virus-associated malignancy. In this study, 218 unrelated patients newly diagnosed with NPC and 196 randomly selected healthy controls from southern China mainland were analyzed for the short tandem repeat polymorphism of exon 5 of MICA gene (MICA-STR) and MICA gene deletion, using fluorescent polymerase chain reaction-gene scanning (PCR/size-sequencing) and polymerase chain reaction-sequence-specific priming (PCR/SSP) technology. MICA*A9 was present at significantly increased frequency in the patient group (P (C)=0.0001002, OR=2.528, 95% CI=1.636-3.907), whereas the frequency of MICA*A5.1 was significantly decreased (P (C)=0.006, OR=0.594, 95% CI=0.437-0.806). Gender-based stratification revealed a significant increase of MICA*A9 frequency (P (C)=0.000072, OR=3.255, 95% CI=1.855-5.709) and a significant decrease of MICA*A5.1 frequency (P (C)=0.000737, OR=0.486, 95% CI=0.337-0.702) in male patients with NPC (N=166), compared with male normal controls (N=120). A significant interaction between MICA*A9 and gender was observed ([see text]=41.58, P=0.0001). Statistics also revealed heterogeneity of effects among MICA*A5.1/MICA*A9-bearing phenotypes and a dose-dependent effect of MICA*A5.1 and MICA*A9 on NPC risk in male subgroup. This constitutes the first demonstration of a gender-specific association between MICA-STR polymorphism and NPC, which could largely be attributable to the underlying gender-related mechanisms that modulate MICA gene expression. The results provide strong supporting evidence suggesting that MICA*A9 may be a genetic risk factor for NPC in male individuals in this population. The potential interaction between MICA and other non-HLA host factors and environmental exposures remains to be further studied.

Adolescent↗

Polymorphism of nine X chromosomal STR loci in Koreans.

This study describes the polymorphism of the nine STR loci on the X chromosome, DXS6803, DXS8378, GATA164A09, DXS7132, DXS7133, DXS9895, DXS9898, DXS6789, and DXS6795 in Koreans. In each locus, 4-10 alleles were noted and the allelic distribution patterns were the same for males and females. Heterozygosity in females ranged from 0.42 to 0.84. Among the 303 father-daughter or mother-child pairs examined 29 cases of mutation were found, 13 at the DXS6803 locus, 2 at DXS8378, 4 at DXS164A09, 3 at DXS7132, 1 at DXS7133, 2 at DXS9895, 2 at DXS9898, 1 at DXS6789 and 1 at DXS6795. In 208 families including 180 fathers and 177 mothers, 530 different haplotypes were found. Unlike the STR loci on the Y chromosome, cases showing recombination were frequent, and in combination with mutation this made it difficult to discriminate the exclusion cases from those with mutation or recombination based on the haplotype. Details of X chromosomal STRs in Koreans which would be useful for a future large scale database are described.

Adult↗

Haplotype analysis with 14 Y-STR loci using 2 multiplex amplification and typing systems in 2 regional populations in Japan.

In this study 14 Y-STR loci (DYS393, DYS19, DYS391, DYS437, DYS435, DYS439, DYS389II, DYS438, DYS436, DYS390, Y-GATA-H4, DYS385, Y-GATA-A7.1 and DYS392) were analysed in 207 Japanese males from Honshu (main island of Japan, Nagoya City) and 87 Japanese males from Okinawa (southernmost islands of Japan) using two multiplex PCR typing systems, a novel 10-plex amplification system and a new commercially available 6-plex typing kit which had two loci in common. The allele frequency distributions were similar at almost all of the 14 loci. Of the haplotypes observed, 244 were unique in both Japanese populations and 17 haplotypes were observed more than once but the 2 populations shared only 7 haplotypes. The haplotype diversities for the 14 loci were 0.9987 and 0.9976 in Honshu and Okinawa Japanese, respectively. The haplotype analysis at 14 Y-STR loci would be useful for personal identification in forensic fields and for population genetics because of the high divergence of these haplotypes.

Chromosomes, Human, Y↗

Y-chromosomal STR haplotypes in a population sample from southwest Germany (Freiburg area).

In the present study Y-chromosomal short tandem repeat (Y-STR) haplotypes of 433 unrelated male individuals from southwest Germany (Freiburg area) were analyzed. Population data for the loci DYS19, 389I, 389II, 390, 391, 392, 393, 385 and YCA II are given. Analysis of these loci provides the data that is defined as the "extended haplotype" and is available in the on-line Y-STR haplotpye reference database (YHRD) at http://ystr.org. Special emphasis is placed on the sequence and nomenclature of YCA II.

Base Sequence↗

A case of double alleles at three Y-STR loci: forensic implications.

In a genetic study of unrelated donors from Bahia (Brazil), one sample contained a 16 Y-STR haplotype with double peaks at three loci: DYS389 II, DYS437 and DYS439. The son of the subject had the same haplotype as found in the father. This profile was compared with a similar case found in a paternity case investigation in Madrid (Spain) and a match was found for the full 16 Y-STR haplotype. Because these three loci are located within the AZFa segment, these results are in accordance with duplication of the AZFa region that includes also other Y-STRs currently used in forensic investigation, for example DYS389I and DYS438. This case attracts our attention in the forensic interpretation of Y-haplotype profiles, because multiple alleles at various loci do not indicate forcibly that the sample under analysis is a mixture.

Brazil↗

Y-chromosomal STR haplotypes in Chinese Uigur ethnic group.

We have already coamplified minimal haplotypes (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385I/II), two additional loci, namely, DYS438, DYS439, and Amelogenin, in a single PCR using the Y-PLEX 12 kit. We investigated 107 unrelated male individuals from the Uigur ethnic group and studied the allelic frequency distribution and haplotype diversity of 11 Y-chromosomal STRs. A number of 43 alleles (nine STR loci) and 27 phenotypes (including DYS385) were detected, with frequencies ranging from 0.0092 to 0.6296. A total of 103 haplotypes were identified, among which 99 were individual-specific and four haplotypes were found twice. The haplotype diversity for these 12 Y-STR loci was 0.9993.

Asian People↗

Haplotyping of STR cluster DXS6801-DXS6809-DXS6789 on Xq21 provides a powerful tool for kinship testing.

Short tandem repeat (STR) markers DXS6801 (GATA41B11), DXS6809 (GATA69B129) and DXS6789 (GATA31F01) are located in a 3-Mb region on human chromosome Xq21, spanning approximately 3-6 cM. Theoretically, this cluster could give rise to 1,144 different haplotypes in the German population. In fact, genotyping of 806 males revealed the presence of 207 different haplotypes. Since the three STRs have been shown to be in strong linkage disequilibrium (LD), haplotype frequencies cannot be computed on the basis of single locus allele frequencies alone, but have to be estimated directly instead. In this work, we present data on linkage, haplotype frequencies and LD in the German population. To highlight the potential of the STR cluster for forensic analysis, we also report two examples of its successful application in pedigree-based kinship testing.

Chromosomes, Human, X↗

Characterisation of variant alleles in the STR systems D2S1338, D3S1358 and D19S433.

We have observed three hitherto undescribed off-ladder alleles at three widely used STR loci. These were isolated, sequenced and designated as follows: allele 10 (D2S1338, one case), allele 21 (D3S1358, two cases) and allele 6.2 (D19S433, six cases). These sequences are described in comparison to non-variant alleles, and their implications for the semi-automated STR analysis will be discussed.

Alleles↗

Evaluation of an extended set of 15 candidate STR loci for paternity and kinship analysis in an Austrian population sample.

We investigated 15 polymorphic short tandem repeat (STR) loci (D1S1656, D7S1517, D8S306, D8S639, D9S304, D10S2325, D11S488, D12S391, D14S608, D16S3253, D17S976, D18S1270, D19S253, D20S161, and D21S1437) which are not included in the standard sets of forensic loci. The markers were selected according to the complexity of the polymorphic region: Of the 15 investigated loci, 7 loci showed a simple repeat structure (D9S304, D10S2325, D14S608, D16S3253, D18S1270, D19S253, and D21S1437), 3 loci (D7S1517, D12S391, and D20S161) consisted of compound repeat units, and 5 loci (D1S1656, D8S306, D8S639, D11S488, and D17S976) showed a more complex polymorphic region partly including different repeat blocks and incomplete repeat units, which resulted in a relatively high proportion of intermediate alleles. A population study on a sample of 270 unrelated persons from Austria was carried out. We did not observe significant deviations from Hardy-Weinberg expectations. The combined probability of exclusion for the 15 loci was 0.99999998. In combination with the conventional set of STR markers included in commercially available kits (no linkage was observed between these 15 loci and the Powerplex 16 System loci), these markers are approved as highly discriminating forensic tools, also suitable for the analysis of difficult paternity and kinship constellations.

Adolescent↗

Y chromosome STR haplotypes in four populations from northwest Africa.

The eight short tandem repeat (STR) polymorphic systems mapping on the male-specific region of the human Y chromosome, DYS19, DYS388, DYS389I, DYS389II, DYS390, DYS391, DYS392 and DYS393, were typed in four populations from northwest (NW) Africa (Moroccan Arabs, southern Moroccan Berbers, Saharawis and Mozabites). Allele frequency distributions showed statistically significant differences for all loci among all the populations except for DYS19. Complete typing was obtained for 185 chromosomes, which showed 74 different haplotypes. The two most frequent haplotypes were found in 16.2% and 15.1% of the individuals, although the latter was almost exclusively found in the Mozabites. Locus and haplotype informativeness were measured by means of the gene diversity (D). The haplotype diversity ranged from 0.856 (Mozabites) to 0.967 (southern Moroccan Berbers). For some loci, allele frequencies in NW Africans were clearly different from those in Europeans. The most common NW African haplotype was found only in one individual out of a total of 494 Europeans typed for the whole STR set. Thus, NW African and European Y chromosomes are clearly differentiated.

Africa, Northern↗

The probability distribution of the number of loci indicating exclusion in a core set of STR markers.

The distribution of the number of loci out of the 13 in the CODIS STR set that would show an exclusion (i.e., a genotype set incompatible either with the prosecution hypothesis or with Mendelian transmission) was estimated in different scenarios. The knowledge of this distribution would provide a framework against which casework evidence can be compared. I used allele frequencies in Iberian and in Italian populations to generate individual genotypes at random and to test in 1 million simulation replicates, how many of the 13 loci would give an exclusion in an individual identification case, a paternity case, and a double parenthood case. All three scenarios were tested under an expected overall exclusion, both for unrelated individuals and for cases in which the suspect or the alleged father was the brother of the real culprit or real father. Paternity and double parenthood cases were also tested in the true scenario, with exclusionary loci due to mutation. In individual identification cases, the average number of exclusionary loci was 11.95 with a minimum of 7. This STR set also showed sufficient power to resolve identification cases in which the evidence sample came from a suspect's sib. False paternity cases yielded an average of 7.65 exclusionary loci and exclusions with only one (0.0108%) or two (0.14%) exclusionary loci were obtained only rarely. The cases of exclusion with one locus could lead to likelihood ratios in favour of paternity, while both true and false paternity cases with two exclusionary loci would often lead to non-conclusive likelihood ratios. The average number of exclusionary loci in a paternity case where the alleged father was the real father's brother was 3.82, with a significant number of cases where no exclusions were obtained.

Child↗

Population data for 12 STR loci in Hong Kong Chinese.

The allele distributions at the 12 short tandem repeat (STR) loci D3S1358, HUMvWA, HUMFIBRA/FGA, HUMTHO1, HUMTPOX, HUMCSF1P0, D5S818, D13S317, D7S820, D8S1179, D21S11 and D18S51 have been determined for 284 unrelated Chinese in Hong Kong. The combined probability of identity for the 12 STR loci was about 4.1 x 10(-14) and the overall probability of excluding paternity 0.999978. None of the 12 loci were found to deviate from Hardy-Weinberg expectations according to the results of the exact test. There was also little evidence for association of alleles between loci. The results demonstrate that the loci are useful for forensic human identification and parentage testing for the Chinese population in Hong Kong.

China↗

Population genetics of ten STR loci (AmpFlSTR SGM plus) in Austria.

A population study on the ten short tandem repeat (STR) loci D3S1358, VWA, D16S539, D2S1338, D8S1179, D21S11, D18S51, D19S433, TH01 and FGA was performed on 204 unrelated Austrian Caucasians. The DNA was amplified by multiplex PCR using the AmpF/STR SGM plus kit. All loci met Hardy-Weinberg expectations. The combined power of exclusion for the ten STR loci was 0.999976. The results show that these loci are very useful for forensic purposes.

Austria↗

STR typing of human telogen hairs--a new approach.

A new approach to short tandem repeat (STR) typing of DNA extracted from telogen shed hairs is presented. Newly designed primer pairs with annealing positions close to the repeat units of the STR loci HUMFES, HUMTH01 and HUMTPOX were used for amplification. The typing results were compared to those obtained by the commonly used primer pairs by means of success rates. The primer pairs capable of producing very short amplicons (< 106 bp with HUMFES, < 86 bp with HUMTH01 and < 87 bp with HUMTPOX) described in this study significantly increased the success rates when typing telogen hairs.

DNA Fingerprinting↗

Parentage testing with 14 STR loci and population data for 5 STRs in the Slovenian population.

In order to apply a set of 14 short tandem repeat (STR) loci in parentage testing, we performed a population genetic study on a sample of 260 unrelated people from the Slovenian population. Genotypes for the 14 STRs were determined using three multiplex polymerase chain reactions (PCR) and automated fluorescent detection. The allele frequencies of the STR loci D5S818, D13S317, D7S820, D8S1179 and D18S51 showed no deviation from the Hardy-Weinberg equilibrium and agreed well with other Caucasian populations. We resolved a series of 181 parentage disputes of which 29 were exclusions. In all cases, evidence for exclusion was obtained by at least 4 informative STRs out of the 14 loci analysed. The 14 loci combined comprise a highly discriminating test suitable for paternity and identity testing in the Slovenian population, with an average estimated mutation rate of 1.2x10(-3), a combined calculated power of exclusion of 99.99974% and paternity index (PI) value of >10(6) in 72% of the inclusion cases and >10(5) in 91% of the inclusion cases.

Genetic Carrier Screening↗