常染色体STR突变基因座父权指数计算

目的概括归纳常染色体STR突变基因座的父权指数计算方法,以在实际检案中应用推广。方法根据目前对常染色体STR基因座突变的认识,用经验递减模型从基因座突变率计算等位基因突变率,分别推导在标准三联体和二联体亲子鉴定中STR突变基因座的父权指数计算式,并举例进行演算。结果总结了在标准三联体鉴定中,只允许假设父突变和既允许假设父也允许母发生突变时,以及二联体鉴定时X和Y的计算式。结论STR基因座发生突变时计算得的父权指数明显低于未发生突变时,提示要检测更多的遗传标记才能使累积父权指数达到认定亲权关系的标准。     

Genetic identification of the mummified fetus

During executing some activities by the police, a mummified human fetus was accidentally revealed on a scrap of paper. It came from pregnancy considerably not carried to term, lasting about 2.5 lunar months. Medical examination did not give evidence of mechanical manipulation such as abortion or disintegration. The aim of the study was the genetic identification of the mummified fetus and an answer to the question if an indicated supposed mother was the mother of the fetus. In the study a relevant factor was maternity confirmation by means of statistic calculations.     

Mutation rates at 14 STR loci in the population from Pernambuco, Northeast Brazil

Definition about mutation rates of short tandem repeats (STRs) loci used in forensic analysis are useful for the correct interpretation of resulting genetic profiles and the definition of criterions for exclusion in paternity testing. Germline mutation of 14 STR loci was studied for 54,105 parent–child allelic transfers from 2575 paternity testing cases carried out during 2000–2007 from the Pernambuco State, Northeast Brazil. The parenthood in each of these cases was highly validated (probability > 99.99%). We identified 43 mutations at 12 loci. Locus-specific mutation rate estimates varied between 2 × 10⁻⁴ and 2 × 10⁻³, and the overall mutation rate estimate was 8 × 10⁻⁴. Mutation events in the male germline were more frequent than in the female germline. The majority of the mutations could be explained by losses or gains of one repeat unit and there was no evidence for selection between insertion or deletion changes. Our data were compared with those of Portuguese and North-American populations for CSF1PO, D18S51, D21S11, D7S820, TH01, TPOX and demonstrated, despite the great difference in the size of the sample, that mutation rates of STR loci in a mixed population do not differ from that encountered in different populations.     

The Upper Silesia (Poland) population and forensic usefulness of 15 autosomal STR loci

Allele frequencies, forensic parameters for the 15 STR loci in the AmpFlSTR^® Identifiler Kit (Applied Biosystems), D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D19S433, VWA, TPOX, D18S51, D5S818 and FGA were determined in a sample of 150 unrelated dead and alive adults from the Upper Silesia region (Poland). The values of heterozygosity (Ht), polymorphic information content (PIC), power of discrimination (PD), matching probability (PM), mean exclusion chance (MEC) and mean exclusion probability (MEP) were calculated. Possible divergence from HWE was determined. Comparison of allele frequencies for examined STR loci between the Upper Silesia population and other Polish populations was carried out.     

Genetic polymorphism of 17 STR loci for forensic use in Chinese population from Shanghai in East China

Allele frequencies for 17 STR loci found in Identifier kit and PowerPlex^®16 Monoplex System were determined in a sample of 1000 unrelated individuals living in Shanghai in East China. The values of observed heterozygosity (Ho), power of discrimination (PD), probability of paternity exclusion (PE) and polymorphism information content (PIC) were calculated. All loci were in accordance with Hardy–Weinberg equilibrium (p < 0.05). The obtained frequency distributions were compared with other previously reported population data.     

ABO genotyping by duplex amplification and oligonucleotide arrays assay

Objective

Research on the application feasibility of ABO genotyping for forensic identification by oligonucleotide arrays assay.

Methods

Oligonucleotide microarrays which detect three different SNPs in exon 6 and exon 7 for ABO genotyping were used. After hybridization wash, the arrays were scanned and fluorescence intensities were analyzed using microarray population studies on ABO was carried out in a sample of 115 unrelated Chinese Han individuals oligonucleotide arrays for genotype detection. The method was also applied to cases.

Results

Technique could identify six genotypes of ABO system and the results of GeneChip analyses confirmed by PCR–RFLP. According to the results of population studies, no significant deviations Hardy–Weinberg equilibrium could be found. The observed heterozygosity (H-obs) was 0.591. Expected heterozygosity (H-exp) was 0.616. The polymorphic information content (PIC) was the average exclusion probability in paternity testing for duos (PE (1)) was 0.188. The average exclusion probability in paternity testing for trios (PE(2)) was 0.344. The discrimination power 0.777.

Conclusion

The data and case application demonstrated that ABO typing by oligonucleotide probe arrays was a useful technique for paternity testing and individual identification.     

Observation of tri-allelic patterns in autosomal STRs during routine casework

We report three cases of tri-allelic patterns observed during routine forensic casework on 5964 Belgian residents. These individuals had been typed for the following 15 autosomal STRs: CSF1PO, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, vWA, FGA, TH01, TPOX, D2S1338 and D19S433.The first example of a tri-allelic pattern had the genotype 13;15;16 for the D8S1179 locus. In the second observation there was 16;21;22 pattern for the D18S51 locus. The third case had the alleles 10;11;13 also for D18S51.All cases belonged to the Type I tri-allelic pattern, with three uneven peaks, the sum of the heights of both smaller peaks equalling the height of the tallest peak.Three cases in 5964 typed individuals is a frequency for tri-allelic patterns in autosomal STRs of 0.05%.     

Sexual assault cases related to unknown perpetrator: Almost 50% of the analyzed cases corresponded to serial offenders

As a collaborative effort in solving sexual assault cases where there is no suspect, the DNA profiles associated with 273 cases were analyzed. Such cases were submitted from different Criminal Investigation Units belonging to eight judicial departments of Buenos Aires Province. A single NN male profile was recovered from the evidences by differential lysis with DNA IQ System (Promega) and typing with IdentiFiler kit. Comparative analysis of the compiled DNA profiles showed that in 45% of the cases the evidence DNA profile matched in at least two unrelated cases. Associations between groups of unsolved cases provided a valuable tool in aiding law enforcement investigations.     

Developmental validation of a Cannabis sativa STR multiplex system for forensic analysis

A developmental validation study based on recommendations of the Scientific Working Group on DNA Analysis Methods (SWGDAM) was conducted on a multiplex system of 10 Cannabis sativa short tandem repeat loci. Amplification of the loci in four multiplex reactions was tested across DNA from dried root, stem, and leaf sources, and DNA from fresh, frozen, and dried leaf tissue with a template DNA range of 10.0-0.01 ng. The loci were amplified and scored consistently for all DNA sources when DNA template was in the range of 10.0-1.0 ng. Some allelic dropout and PCR failure occurred in reactions with lower template DNA amounts. Overall, amplification was best using 10.0 ng of template DNA from dried leaf tissue indicating that this is the optimal source material. Cross species amplification was observed in Humulus lupulus for three loci but there was no allelic overlap. This is the first study following SWGDAM validation guidelines to validate short tandem repeat markers for forensic use in plants.     

Characterization of 26 miniSTR loci for improved analysis of degraded DNA samples

An additional 20 novel mini-short tandem repeat (miniSTR) loci have been developed and characterized beyond the six previously developed by our laboratory for a total of 26 non-CODIS miniSTR markers. These new markers produce short PCR products in the target range of 50-150 base pairs (bp) by moving the primer sequences as close as possible-often directly next to the identified repeat region. These candidate loci were initially screened based on their small amplicon sizes and locations on chromosomes currently unoccupied by the 13 CODIS STR loci or at least 50 Mb away from them on the same chromosome. They were sequenced and evaluated across more than 600 samples, and their population statistics were determined. The heterozygosities of the new loci were compared with those of the 13 CODIS loci and all were found to be comparable. Only five of the new loci had lower values than the CODIS loci; however, all of these were much smaller in size. This data suggests that these 26 miniSTR loci will serve as useful complements to the CODIS loci to aid in the forensic analysis of degraded DNA, as well as missing persons work and parentage testing with limited next-of-kin reference samples.