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Human genome diversity initiative.
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Establishing the robustness of short-tandem-repeat statistics for forensic applications.
Before the introduction of a four-locus multiplex short-tandem-repeat (STR) system into casework, an extensive series of tests were carried out to determine robust procedures for assessing the evidential value of a match between crime and suspect samples. Twelve databases were analyzed from the three main ethnic groups encountered in casework in the United Kingdom: Caucasians, Afro-Caribbeans, and Asians from the Indian subcontinent. Independence tests resulted in a number of significant results, and the impact that these might have on forensic casework was investigated. It is demonstrated that previously published methods provide a simple procedure for correcting allele frequencies--and that this leads to conservative casework estimates of evidential value.
Mitochondrial D-loop "signatures" produced by low-stringency single specific primer PCR constitute a simple comparative human identity test.
We have developed a technique called "LSSP-PCR" (low-stringency single specific primer PCR) that detects single or multiple mutations in DNA. A purified DNA fragment is submitted to PCR by using a single primer specific for one of the extremities of the fragment, under conditions of very low stringency. The primer hybridizes specifically to its complementary extremity and nonspecifically to multiple sites within the fragment, in a sequence-dependent manner. A complex set of reaction products is thus created that, when separated by electrophoresis, constitutes a unique "gene signature." We here report the application of LSSP-PCR to the detection of sequence variation in the control (D-loop) region of human mtDNA, which is known to differ significantly between unrelated individuals. We prepared human DNA samples from blood and amplified a 1024-bp portion of the mtDNA control region, using primers L15996 and H408. The amplified mtDNA fragments were then reamplified under LSSP-PCR conditions by using L15996 or H408 as drivers to produce complex signatures that always differed between unrelated individuals and yet were highly reproducible. In contrast, all mother-child pairs tested were identical, as expected from the matrilineal inheritance of mtDNA. Thus, the use of LSSP-PCR to produce D-loop signatures constitutes a powerful new technique for mtDNA-based comparative identity testing.
Testing the feasibility of DNA typing for human identification by PCR and an oligonucleotide ligation assay.
The use of DNA typing in human genome analysis is increasing and finding widespread application in the area of forensic and paternity testing. In this report, we explore the feasibility of typing single nucleotide polymorphisms (SNPs) by using a semiautomated method for analyzing human DNA samples. In this approach, PCR is used to amplify segments of human DNA containing a common SNP. Allelic nucleotides in the amplified product are then typed by a colorimetric implementation of the oligonucleotide ligation assay (OLA). The results of the combined assay, PCR/OLA, are read directly by a spectrophotometer; the absorbances are compiled; and the genotypes are automatically determined. A panel of 20 markers has been developed for DNA typing and has been tested using a sample panel from the CEPH pedigrees (CEPH parents). The results of this typing, as well as the potential to apply this method to larger populations, are discussed.
Analysis of the VNTR locus DXS52 by the Amp-FLP technique.
The locus DXS52 is useful genetic marker system for forensic analysis. It consists of a variable number of tandem repeats (VNTR) and can be analyzed by the Amp-FLP technique. As accurate data about the distribution of the alleles are among the most important prerequisites for the application in forensic biology, we studied the allele distribution of DXS52 locus in a Chinese population and applied the established technique to paternity testing.
Analysis of the short tandem repeat systems HUMF13B and HUMvWF in Chinese (Liaoning).
The short tandem repeat (STR) systems HUMF13B and HUMvWF were investigated in 200 healthy Chinese individuals living in Liaoning (The northeast of China). The HUMF13B allele frequencies were 6 = 0.0025, 8 = 0.1825, 9 = 0.1750, 10 = 0.6325 and 11 = 0.0075; and the HUMvWF allele frequencies were 13 = 0.0300, 14 = 0.2475, 15 = 0.0450, 16 = 0.1750, 17 = 0.2600, 18 = 0.1525, 19 = 0.0725 and 20 = 0.0175. The distribution of genotypes corresponded to the Hardy-Weinberg equilibrium. The distinguishing probabilities (D.P) were calculated as 0.7318 and 0.9366; the polymorphism information content (PIC) were calculated as 0.4827 and 0.7822; and the heterozygosity (h) were calculated as 0.5378 and 0.8128, respectively. The HUMF13B and HUMvWF systems provide a useful genetic marker for human genetics, anthropological studies, and forensic science in the chinese population.
The evaluation of forensic DNA evidence. Excerpt from the Executive Summary of the National Research Council Report.
The following is an excerpt from the Executive Summary of the National Research Council Report.
Individualisation of dental tissue--an aid for odontological identification?
The introduction of new methods in forensic diagnostics, especially serological techniques, including the use of individual markers for identification is becoming increasingly important. The DNA techniques are particularly promising and dental tissue, especially dental pulp, is a good source of DNA because it is well protected against autolysis. Gc-subtyping and application of DNA techniques for identification were reported in 1992 and show the efficacy of PCR systems for the individualisation of dental tissues. In cases of optimal conditions-room temperature and dry air-the analysis was successful after 6 or 12 months and the results could be used for identification. Under the influence of high temperature autolysis occurs and the pulp degrades making DNA typing almost impossible. The experiments show that the system HLA-DQ alpha is more reliable than the system MCT 118 and the results confirm that these techniques can be used for identification of unknown persons in some cases. The methods are only usable if comparative material belonging to the subject, such as hair, is available.
Determination of sibship by microsatellite typing in a deficiency case of disputed maternity: further study.
In a deficiency case of maternity dispute where the father and his two wives were dead and only the six children were available for testing, we analyzed three sex-linked short tandem repeat (STR) loci DYS19, HPRT, and AR. On the basis of the typing results of the HPRT and AR loci, we obtained probabilities of maternity ranging from 0.9256 to 0.9724 for five of the six children. The results supported those of typing for 24 conventional hemogenetic markers and 11 autosomal STRs, enabling us to establish maternity. The present study demonstrates the utility of sex-chromosomal STR typing in the solution of deficiency cases of disputed parentage.
Comparison of a hypervariable segment in the human dopamine D4 receptor (DRD4) gene between the Japanese and Mongolian populations.
Amplifiable length polymorphism (AmpFLP) genotyping and direct sequencing of a hypervariable segment in the human dopamine D4 receptor (DRD4) gene were performed from genomic DNA of 100 unrelated Japanese and Mongolian individuals. The 4-repeat allele (314 bp) was the most prevalent and appeared at 0.88 and 0.82 in the Japanese and Mongolian populations, respectively. Homogeneity test of distribution showed no significant deviation from the observed frequencies of genotypes between the Japanese and Mongolian populations, but sequence analysis of the 4-repeat allele indicated that there could be ethnic differences between the two populations at the nucleotide level. The DRD4 allele and genotype frequencies in 10 patients with Parkinson's disease did not differ from those in the control Japanese population. In one Parkinsonian patient, however, a nucleotide change in one of the 4-repeat alleles was discovered. These results suggest that there could be ethnic and/or individual differences in the specific nucleotide changes within the repeat sequence because some alleles with the same number of repeat units had sequence variations. Thus, the DRD4 polymorphism exists at two levels and therefore could be a useful marker for forensic identification and anthropological studies.
Metric and comparative analysis of sexual dimorphism in the Thai femur.
Identification of sex from the skeleton is an important demographic assessment in medicolegal investigations. Studies have demonstrated that populations differ from each other in size and proportions and that these differences can affect the metric assessment of sex. It is therefore vital to determine if population differences are great enough to necessitate group-specific standards. To date, there have been no attempts to create standards of assessment for modern Thais. Therefore the purpose of this research is to establish standards from which to determine sex from the femur using a new skeletal collection housed at the Chiang Mai University Department of Anatomy. The sample is composed of 104 individuals (70 males, 34 females). Six standard osteometric dimensions including maximum length, maximum head diameter, midshaft circumference, midshaft anterior-posterior and transverse diameters, and bicondylar breadth were measured and analyzed by stepwise discriminant function statistics. To understand population differences, formulas derived from Chinese, South African whites and American whites and blacks using the same method and variables were tested on the Thai sample. Results indicated that maximum head diameter and bicondylar breadth are the optimal combination for sex diagnosis and yielded 94.2% accuracy. Direct analysis using predetermined single or multiple variables also revealed bicondylar breadth as the best single dimension (93.3%). In cross-tests on the Thais, the Chinese formula gave the most favorable outcome with unsatisfactory results for all other groups. The present research confirms that sexual dimorphism is better reflected in breadth dimensions than in bone length. Comparisons showed that Thais are very different metrically from whites and blacks, and although they most resemble the Chinese, these two groups are not identical. These findings underscore the need for population-specific formulas for identification of sex from the skeleton.
[The physician and medicine in the new penal code].
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[Recent developments of genetic markers in legal practice].
The human identification in forensic science is currently based upon the study of highly polymorphic systems with mendelian transmission: the STRs (Short Tandem Repeats). These genetic markers are three to seven bases repetitive sequences spread all over the genome. They are detected by using the Polymerase Chain Reaction (PCR). This analysis method makes it possible to amplify several different loci from very low quantities of genomic DNA (Desoxyribonucleic Acid) in very short periods of time without using any radioactive substances. Interpretation of the results is simple because the amplified fragments are of a known size. The alleles known in each system with discrete values allow the calibration of the revealing gel and the populations studies; moreover, they may be entered into a database. The fragility of this test implies specific precautions with the Laboratory's organization in order to avoid any kind of contamination. Both the establishment of a quality assurance responding to the ISO 9002 standard together with internal quality controls would ensure that these tests are reliable and repeatable in the opinion of the Courts. Only authorized laboratories may perform DNA testing on the occasion of legal proceedings.
[Simultaneous phenotyping of proteins with various pHs by complex IEF and its application in forensic haemogenetics].
We have developed a new technique of complex isoelectric focusing (IEF) by which various proteins with different pHs can be detected out in polyacrylamide gels containing ampholytes with different pH ranges at the same time. The success of phenotyping 12 human proteins by this technique proved it was reliable and efficient. The cumulative Epp and the cumulative Dp reached 0.9 and 0.9999 respectively. It provides a new approach to analysis of genetic markers in the field of forensic haemogenetics.
DNA typing revealing high HLA-Cw polymorphism completes availability of major histocompatibility complex loci in forensic medicine.
Studies of human population genetics in Hungary have revealed relevant heterogeneity in the major histocompatibility complex. In the present studies, two isolated ethnic groups were chosen: people living in the Káli Basin westward from the Danube River, and those living in Opusztaszer, a village eastward from Danube, who are known as native ancient Hungarians. Blood samples were collected from 70 people in the Káli Basin and from 45 people in Opusztaszer. The frequency of HLA-Cw alleles was determined by serology as well as by DNA typing in 46 and 32 samples of the two populations, respectively, and in 44 randomly selected subjects of Hungarian origin. Compared with a random population of cadaver donors (the deaths having resulted mostly from accidents or, in a smaller number, strokes or heart infarcts) and voluntary bone marrow donors (typed in the last 10 years) recruited from all parts of Hungary and representing the mixed Hungarian population, remarkable differences were found in haplotype and allele frequencies. HLA-A, -B, -Cw typing was performed by serology and, in the case of the HLA-Cw locus, by polymerase chain reaction (PCR)-SSP and/or PCR-SSOP techniques, as well. The PCR-SSO oligotyping procedure allowed the identification of 32 Cw alleles in contrast with the 9 serologically detectable types. Because of the combination of low antigen expression and the lack of specific serologic reagents of good quality, no HLA-Cw antigens were detectable in 41%, and only one was detected in 48%, of the investigated individuals by standard serologic typing. With PCR-SSO typing, however, 97% of the investigated individuals proved to be heterozygous for HLA-Cw alleles. The two isolated populations differed from each other, from mixed Hungarian and other Caucasian populations in HLA-Cw* allele frequencies, as well as in haplotype distribution. This newly recognized polymorphism at the HLA-Cw locus completes the availability of major histocompatibility complex typing in forensic science and practice.
[Biotinylated Y chromosome specific probe for human sexing].
Human chromosome DNA from WBC or fetus chorion samples were digested with Hae III and hybridized with biotinylated Y chromosome specific probe by Southern blotting, and hybridization signals were developed by the ABC (Avidin-biotin-alkaline phosphatase complex) system. The hybridization signal for 0.1 microgram of male DNA could be detected clearly, while the signal for even 5 micrograms of female DNA could not. Parallel tests showed that the sexing results using 32P-labeled and biotinylated Y probe were identical. This suggests that the biotinylated Y probe can be applied to the determination of X-linked genetic diseases and sex abnormality, forensic analysis, sex determination of sportsmen and women, heterosexual transplantation of bone marrow, etc. It could become a convenient means for genetic diagnosis.
[Genetic variability and discriminating power of four microsatellite loci in Russian population].
Allele and genotype frequencies of 4 STR loci (LPL, vWA, FES/FPS H F 13B), used in forensic medicine, were analyzed in Russian Siberian population. Genetic and molecular diversity of these polymorphic systems were characterized in comparison with US Caucasoid population. High discriminating power (PD = 0.99975) of the system of four studied STR loci was shown. Comparative analysis of genetic diversity in Russian population and Caucasoid US population revealed the significant differences between two populations and demonstrated that STR frequency data for US population should not be used for forensic expertise in Russia. The data obtained in the current investigation may be used as reference data for forensic medicine laboratories in Siberia.