Ines Plate

Sequence variation and allele nomenclature for the X-linked STRs DXS9895, DXS8378, DXS7132, DXS6800, DXS7133, GATA172D05, DXS7423 and DXS8377.

X-linked DNA markers are increasingly used in forensic kinship testing. This paper presents sequencing data of the short tandem repeats (STRs) DXS9895, DXS8378, DXS7132, DXS6800, DXS7133, GATA172D05, DXS7423, DXS8377 and proposes an allele nomenclature. Alleles were assigned according to the recommendations of the International Society of Forensic Genetics (ISFG) Commission.

The STR cluster DXS10148–DXS8378–DXS10135 provides a powerful tool for X-chromosomal haplotyping at Xp22

The evaluation of four pairs of tightly linked chromosome X (ChrX) short tandem repeat (STR)s at Xp22, Xq12, Xq26 and Xq28 led to the creation of the Argus X 8 multiplex amplification kit. These eight STRs are distributed as four closely linked pairs over the entire X-chromosome, and for practical reasons, they are assigned to four linkage groups 1–4. To achieve a further considerable enhancement in discrimination power, we suggest to include additional markers. A recent paper referred to the earlier evaluation of STR clusters at Xq12, Xq26 and Xq28, and here we present the pending data of linkage group 1 at Xp22. The newly established STR updates the Xp22 STR cluster which now presents three polymorphic markers: DXS10148 (PIC = 0.8556), DXS10135 (PIC = 0.9093) and DXS 8378 (PIC = 0.6454). Typing of 398 X-chromosomes provided 278 different and 200 unique haplotypes. All the other haplotypes observed appeared with frequencies in the range between 0.005 and 0.015. Considering this STR triple in the context with the three further triple clusters Xq12, Xq26 and Xq28 published earlier, we announced the development of a next generation of a ChrX STR cluster typing kit.

Population Data on the X Chromosome Short Tandem Repeat Locus HumHPRTB in Two Regions of Germany

This report contains the results of two population studies on the X chromosome STR HumHPRTB carried out in a Northern and a Southern region of Germany. The numbers of unrelated individuals were 443 and 335, respectively. Eight alleles (alleles 9 to 16) were found. In female individuals 29 different genotypes were encountered. In German populations the HumHPRTB STR was characterized by the following data: PIC = 0.750; HET = 0.769: MEC = 0.556. Allele distribution met the Hardy-Weinberg expectations. The Northern and Southern populations did not show any significant differences.

Forensic mass screening using mtDNA

At the forensic autopsy of a sexual murder victim, some trace hairs, possibly belonging to the perpetrator, were saved. Initially, the analysis of a pubic hair shaft only revealed the presence of the mitochondrial (mt) DNA haplotype profile consisting of the (CA)6 allele and the complete hypervariable region 1 (HV1) and 2 (HV2) sequence. Later, typing of some further telogene trace hairs, which had been stored for several years, yielded a nuclear short tandem repeat (STR) profile. We used both the mtDNA haplotype and the STR profile to start a DNA mass screening project involving 2,335 male citizens of the relevant communities. MtDNA screening was carried out by using the CA repeat amplification in combination with an SNP typing procedure based on the restriction site analysis of amplified d-loop sequences. The aim of our paper is to put mass screening with mtDNA up for discussion.

Efficiency of forensic mtDNA analysis: Case examples demonstrating the identification of traces

The paper presents results of forensic mitochondrial DNA analyses which were aimed at typing the traces caused by touching or abrasion of skin cells. Five cases of strangulation tool investigation are summarised. Two cases of homicide could be cleared up by identifying the mtDNA of both the victim and the suspect on cables which had obviously been used as strangulation tools. In eight of 10 cases, weapons could be reliably assigned to their users. The mtDNA of the users could be even detected on cartridges after firing. In one case, evidence of a suicide could be provided by means of mtDNA sequencing of the wiping traces on a suicide note.

DXS10011: studies on structure, allele distribution in three populations and genetic linkage to further q-telomeric chromosome X markers

The hypervariable tetranucleotide STR polymorphism DXS10011 is a powerful marker for forensic purposes. Investigation of this STR led to an allele nomenclature which is in consensus with the ISFG recommendations. DXS10011 is located at Xq28 and genetically closely linked to DXS7423 and DXS8377 but is unlinked to HPRTB and more distant X-chromosomal STRs. DXS10011 is a very complex marker exhibiting some structural variants within alleles of identical length. Two types of repeat structure (regular and inter-alleles) are known and described as types A and B. Two SNPs which are in strong linkage disequilibrium to the different sequence types were found in the repeat flanking region. The type A sequence consists of a long stretch of uninterrupted homogenous repeats which is highly susceptible to slippage mutation during male meiosis.

Chromosome X haplotyping in deficiency paternity testing principles and case report

Abstract This paper presents an example of deficiency paternity testing by using 15 chromosome X (ChrX) markers. The special power of ChrX typing in deficiency kinship testing is demonstrated. In the case of investigation, ChrX haplotyping confirmed the claim of the disputed offspring to be related to the deceased putative father.

Mitochondrial D-loop (CA)n repeat length heteroplasmy: frequency in a German population sample and inheritance studies in two pedigrees

Sequence analysis of the human mitochondrial genome (mtDNA) has proven to be a valuable tool in forensic identity testing and the analysis of crime scene stains. In contrast to the very expensive sequencing technique, typing of different length variants can greatly facilitate screening of a large number of traces for their relevance during casework. Within the mitochondrial control region, a dinucleotide (CA)n repeat locus is present. To assess the discrimination power of this marker, we have determined (CA)n allele distribution and the frequency of heteroplasmy in a population sample of 2,458 Germans. The inclination to develop heteroplasmic mixtures (CA)n/(CA)n−1 was positively correlated with the number of CA repeats in the mtDNA. In addition, we have studied the inheritance patterns of (CA)n repeat sequence heteroplasmy in two pedigrees. In one pedigree, we also found a length heteroplasmy in the homopolymeric C-tract (nt 303–309). Our data show stable inheritance of heteroplasmy within the homopolymeric C-stretch, but rather unstable inheritance regarding the (CA)n repeat locus.

Population genetic data of the STR HumD3S1358 in two regions of Germany

Abstract This report gives the results of two population studies on HumD3S1358 from a northern and a southern region of Germany. The numbers of unrelated individuals were 326 and 666, respectively and seven main alleles, three rare allelic variants and 29 different genotypes were encountered. No significant statistical differences were seen between the northern and southern populations. The HumD3S1358 allele distributions were in agreement with Hardy-Weinberg expectations and two mutations were found in 780 meiotic events.

Heteroduplex Analysis is a Rapid Method for the Detection of Suballeles Caused by Mixed Length and Sequence Variability in Short Tandem Repeat Systems

STR polymorphisms differ in the number of the tandem repeats. However, in addition, a microheterogenity, as far as the sequence variation is concerned, has been detected in some systems (HumVWA and others) (Moller 1994). The aim of our paper is to demonstrate the usefulness of the heteroduplex (HD) analysis (HDA) for the detection of suballeles in DNA systems such as HumVWA (Kimpton 1992), HumCD4 (Edwards 1991) and Hum Dysl9 (Roewer 1992). The HDA is a well-established technique (Wilkin 1993) but, to our knowledge, HDA is not usual in forensic application. During PCR amplification, the DNA products are submitted to a melting and a reassociation process. In case of a homozygous genotype, the reassociation produces only homoduplexes. However, if there are DNA fragments with different numbers of repeats and/or significant differences concerning the sequence, the reciprocal association produces two or more types of HDs in addition to homoduplexes. On dependency on the extension of the missmatch area, the HDs migrate noticeably slower than homoduplexes in the nativePAGE. Thus, HD can provide several pieces of information which remain hidden, if only measurements of the length are performed.