Mutation rate analysis at 19 autosomal microsatellites.

Previous studies have demonstrated that a large sample size is needed to reliably estimate population- and locus-specific microsatellite mutation rates. Therefore, we conducted a long-term collaboration study and performed a comprehensive analysis on the mutation characteristics of 19 autosomal short tandem repeat (STR) loci. The STR loci located on 15 of 22 autosomal chromosomes were analyzed in a total of 21,106 samples (11,468 parent-child meioses) in a Chinese population. This provided 217,892 allele transfers at 19 STR loci. An overall mutation rate of 1.20 × 10(-3) (95% CI, 1.06-1.36 × 10(-3) ) was observed in the populations across 18 of 19 STR loci, except for the TH01 locus with no mutation found. Most STR mutations (97.7%) were single-step mutations, and only a few mutations (2.30%) comprised two and multiple steps. Interestingly, approximately 93% of mutation events occur in the male germline. The mutation ratios increased with the paternal age at child birth (r = 0.99, p<0.05), but not maternal age. Last, with the combination analysis of the data from the southern Chinese population, we drew a picture of 19 STR mutations in China. In conclusion, the data from this study will provide useful information in parentage testing, kinship analysis, and population genetics.

[Mutation of suspected autosomal STR loci: 227 cases retrospective analysis].

OBJECTIVE: To study the suspected autosomal STR loci mutation cases. METHODS: A total of 227 suspected autosomal STR loci mutation cases were selected from Center of Forensic Sciences, Beijing Genomics Institute. The allelic mutation cases were screened and the number of mutation of each STR loci was statistically analyzed. The CPI value was calculated in order to study the characteristics and rules of the mutations. RESULTS: In the 227 suspected mutation cases, 3 cases were excluded paternity, and 228 mutations were observed at 18 STR loci in the rest of the cases. The average number of STR mutation loci was 1-2. The maximum of mutation step was 4. After using 20A amplification kit, the CPI values in 3 non-parentage cases were all less than 10(4). After using 20A and 10G amplification kits, the CPI values were all larger than 10(4) in all standard parents-child triplet cases and in 99.45% of diad cases. CONCLUSION: The allelic mutation of STR loci is relatively common in forensic cases. By increasing the number of the required STR loci and supplementing the samples of the triplet, the identification errors could be decreased to a great extent when suspected autosomal STR loci mutation occurs.

Genetic polymorphism analysis of 15 STR loci in Chinese Hui ethnic group residing in Qinghai province of China.

In the present study, we investigated the diversity distributions of allelic frequencies of 15 short tandem repeats (STRs) loci in a sample of Chinese Hui ethnic group in the Ningxia Hui Autonomous Region. The allelic frequencies of the 15 STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA) were obtained from 2975 unrelated healthy Hui individuals. The STR genotyping data of all the samples were generated by DNA extraction, multiple amplification, GeneScan and genotype analysis. The genetic distances among different populations were calculated by using Nei's method and a phylogenetic tree was constructed based on the allelic frequencies of the same 15 STR loci using the neighbor-joining method. A total of 185 alleles were observed in the Hui population, with the corresponding allelic frequencies ranging from 0.0002 to 0.5322. Chi-Square tests showed that all STR loci were in Hardy-Weinberg equilibrium. The forensic statistical parameters of all the loci showed high values. The population data in this study were compared with the previously published population data from other ethnics or areas. The Hui population showed significant differences from the Minnan Han, Uigur, Ewenki, Yi, Tibetan, Maonan and Malay ethnic minority groups in some loci, and from the South Morocco population and the Moroccan population in all the loci. Our results are valuable for human individual identification and paternity testing in the Chinese Hui population and are expected to enrich the genetic information resources of Chinese populations.

[Detection of ABO genotype genetic polymorphism by multiplex-PCR based sequencing and application in forensic medicine].

Multiplex PCR-direct sequencing method was established to detect 9 different SNPs in exon 6 and exon 7 of ABO genes and could identify at least 28 different ABO genotypes. Population study was carried out in a sample of 80 unrelated Chinese Tibetan minority individual dwelled in Qinghai Province. The method was also applied to forensic cases. A variety of degeneration forensic samples, including blood stain, hair root, swab, bone and mixed stain were successfully identified by this efficient method and in conformance with serological typing. There were no significant deviations from Hardy-Weinberg equilibrium in ABO genotypes of Tibetan population. The heterozygosity, polymorphic information content, discrimination power, paternity of exclusion, and probability of genetic identity were 0.675, 0.672, 0.874, 0.391, and 0.126 respectively. The gene frequency of ABO was O>B>A. The multiplex PCR-directed sequencing method can accurately and reliably detect ABO genotypes in many kinds of samples, and it improves personal identification efficiency. The ABO genotype is high variance in Qinghai Tibetan minority group, and it can be applied in forensic medicine and population genetic study.

[Sequence polymorphism of mtDNA control region in Chinese Qinghai Tibetan ethnic group and Han population].

OBJECT: To study sequence polymorphism of mtDNA control region in Chinese Qinghai Tibetan group and Han population. METHODS: Venous blood samples from 69 unrelated Qinghai Tibetans and Han individuals were collected and their mtDNA control region sequences were analyzed. Polymorphism indicators were calculated. The genetic distances based on Fst and Rst among eleven groups from different districts include the Qinghai Tibetan and Han population were elucidated using Nei's method. Phylogenetic tree was constructed. RESULTS: There were 56 polymorphic loci and 59 loci found in the mtDNA control region of Tibetan group and Han population, respectively. It was indicated by the Rst distance that there was a far distance between Qinghai Tibetan and the other populations (P<0.05), and the distance was much closer between Qinghai Han and Xi'an Han, Mongolian, Changsha Han populations (P>0.05). CONCLUSION: There is unique genetic polymorphism of mtDNA control region both in Qinghai Tibetan and Han population. These findings may be useful in forensic identification, population genetic and migration studies.

Genetic analysis of 15 STR loci in Chinese Han population from West China.

Allele frequencies for 15 short tandem repeat (STR) loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818, and FGA) were obtained from 7,636 unrelated individuals of Chinese Han population living in Qinghai and Chongqing, China. Totally 206 alleles were observed, with the corresponding allele frequencies ranging from 0.0001-0.4982. Chi-square test showed that all of the STR loci agreed with the Hardy-Weinberg equilibrium. We also compared our data with previously published population data of other ethnics or areas. The results are valuable for human identification and paternity testing in Chinese Han population.