Hanna E. Hansen

Performance of the SNPforID 52 SNP-plex assay in paternity testing

The performance of a multiplex assay with 52 autosomal single nucleotide polymorphisms (SNPs) developed for human identification was tested on 124 mother-child-father trios. The typical paternity indices (PIs) were 10(5)-10(6) for the trios and 10(3)-10(4) for the child-father duos. Using the SNP profiles from the randomly selected trios and 700 previously typed individuals, a total of 83,096 comparisons between mother, child and an unrelated man were performed. On average, 9-10 mismatches per comparison were detected. Four mismatches were genetic inconsistencies and 5-6 mismatches were opposite homozygosities. In only two of the 83,096 comparisons did an unrelated man match perfectly to a mother-child duo, and in both cases the PI of the true father was much higher than the PI of the unrelated man. The trios were also typed for 15 short tandem repeats (STRs) and seven variable number of tandem repeats (VNTRs). The typical PIs based on 15 STRs or seven VNTRs were 5-50 times higher than the typical PIs based on 52 SNPs. Six mutations in tandem repeats were detected among the randomly selected trios. In contrast, there was not found any mutations in the SNP loci. The results showed that the 52 SNP-plex assay is a very useful alternative to currently used methods in relationship testing. The usefulness of SNP markers with low mutation rates in paternity and immigration casework is discussed.

Paternity testing with VNTR DNA systems

SummaryPaternity testing was carried out in 271 cases of disputed paternity using the 5 VNTR systems D2S44 (YNH24), D5S43 (MS8), D7S21 (MS31), D7S22 (g3), and D12S11 (MS43a), and 10–15 conventional marker systems including the HLA-A,B system. By means of the matching criteria for the VNTR systems established elsewhere (Morling & Hansen 1992), all 70 unrelated men who had been excluded by conventional typing were also excluded with 2 or more VNTR systems. Based on the observed exclusion frequencies for the 5 VNTR systems, a theoretical exclusion rate exceeding 0.999 could be obtained. A total of 350 father/child pairs were studied and in 3 paternity cases and one immigrant family, the alleged fathers were excluded solely by one of the 5 VNTR systems possibly reflecting mutations. No mother/child exclusions were observed among 350 mother/child pairs. Linkage analysis between the syntenic systems D7S21 (MS31) and D7S22 (g3) was performed in 29 informative families with 81 children and revealed a recombination distance of about 31 cM. The positive evidence for paternity provided by the 5 VNTR systems in cases with non-exclusions is discussed.ZusammenfassungVaterschaftstests wurden in 271 Fällen strittiger Vaterschaft mit Hilfe der 5 VNTR-Systeme: D2S44 (YNH24), D5S43 (MS8), D7S21 (MS31), D7S22 (g3), D12S11 (MS43a) und 12–15 konventionellen Blutgruppensystemen einschließlich des HLA-Systems (HLA A und B) durchgeführt. Mit Hilfe der Matching-Kriterien für VNTRSysteme, wie sie andernorts (Morling und Hansen 1992) etabliert wurden, wurden alle 70 unverwandten Männer, die durch konventionelle Typisierung ausgeschlossen wurden, auch mit Hilfe von 2 oder mehreren VNTR-Systemen ausgeschlossen. Basierend auf den beobachteten Ausschlußfrequenzen für die 5 VNTR-Systeme könnte eine theoretische Ausschlußwahrscheinlichkeit von mehr als 0,999 erhalten werden. Insgesamt wurden 350 Vater/Kind-Paare untersucht und in 3 Vaterschaftsfällen und einer Emigrantenfamilie wurden isolierte Ausschlüsse der Putativväter ausschließlich in einem der 5 VNTR-Systeme gefunden, was möglicherweise an Mutationen denken läßt. Unter 350 Mutter/Kind-Paaren wurden keine Mutter/Kind-Ausschlüsse gefunden. Linkage-Analysen zwischen den Syntenic-Systemen D7S21 (MS31) und D7S22 (g3) wurden durchgeführt an 29 Familien mit 81 Kindern. Die Analyse ergab eine Rekombinationsdistanz von ungefähr 31 cM. Der positive Vaterschaftsbeweis, wie er durch die 5 VNTR-Systeme in Fällen mit Nicht-Ausschlüssen etabliert wird, wird diskutiert.

Paternity testing with VNTR DNA systems: I. Matching criteria and population frequencies of the VNTR systems D2S44, D5S43, D7S21, D7S22, and D12S11 in Danes

SummaryPaternity testing using DNA polymorphism of variable numbers of tandem repeat (VNTR) regions with restriction fragment length polymorphism (RFLP) was implemented. HinfI-digested DNA was separated by electrophoresis in agarose gels and hybridized with radiolabelled probes detecting the VNTR-systems D2S44 (YNH24), D5S43 (MS8), D7S21 (MS31), D7S22 (g3), and D12S11 (MS43a). The intra gel variability of 970 duplicate investigations on the same gel of DNA from 122 individuals showed no differences exceeding 1.25 mm between the positions of the corresponding DNA fragments. The comparison of 1,624 DNA fragments from 342 mother/child pairs showed only one difference above 1.25 mm which was interpreted as a mutation. Based on these observations, we decided to consider an intra gel difference above 1.25 mm between the non-maternal DNA fragment of the child and the nearest DNA fragment of the putative father as an exclusion in paternity testing. This matching criterion was used for the comparisons of 1,197 DNA fragment differences in 247 pairs of children and putative fathers who had not been excluded by conventional marker systems. In all of these cases, the migration differences between the DNA fragments of non-excluded men and the DNA fragments of the children were less than 1.25 mm except in 6 cases (0.5%). The man/child differences in all of 227 false trios exceeded 1.25 mm in 2 or more of the 5 VNTR systems investigated. Matching criteria for inter gel comparisons in paternity testing were established. The frequency distribution of Hinfl digested DNA fragments of the 5 VNTR systems in 650 unrelated Danes is presented and the raw data is available.ZusammenfassungDNA-Polymorphismen mit einer variablen Anzahl von tandemähnlichen Wiederholungseinheiten (VNTRs), speziell der Typus der Restriktionsfragmentlängenpolymorphismen, wurden in die Vaterschaftsanalyse eingeführt. Hinfl-verdaute DNA wurde elektrophoretisch in Agarose-Gelen aufgetrennt und mit radioaktiv markierten Sonden hybridisiert, welche die VNTR-Systeme D2S44 (YNH24), D5S43 (MS8), D7S21 (MS31), D7S22 (G3) und D12S11 (MS43a) detektieren. Die sog. Intra-Gelvariation von 970 Doppeluntersuchungen auf demselben Gel von DNA von 122 Personen zeigte keine Unterschiede, welche größer waren als 1,25 mm — bezogen auf die Positionen der korrespondierenden DNA-Fragmente. Der Vergleich von 1.624 DNA-Fragmenten von 342 Mutter—Kind—Paaren zeigte lediglich einen Unterschied, welcher größer als 1,25 mm war und daher als eine Mutation interpretiert wurde. Hierauf basierend entschlossen wir uns, eine Intra-Geldifferenz größer als 1,25 mm zwischen dem nicht-mütterlichen DNA-Fragment des Kindes und dem nächsten DNA-Fragment des Putativ-Vaters als einen Ausschluß in der Vaterschaftsanalyse zu bewerten. Dieses Match-Kriterium wurde benutzt für die Vergleiche von 1.197 DNA-Fragmentdifferenzen bei 247 Paaren von Kindern und Putativ-Vätern, bei welchen in konventionellen Systemen kein Ausschluß zu beobachten war. In all diesen Fällen waren die Wanderungsunterschiede zwischen DNA-Fragmenten der nicht-ausgeschlossenen Männner und den Fragmenten der Kinder geringer als 1,25 mm mit der Ausnahmen von 6 Fällen (0,5%). Die Mann—Kind—Differenzen in allen der 227 falschen Terzette überschritten 1,25 mm in zwei oder mehr der 5 VNTR-Systeme, welche untersucht wurden. Match-Kriterien für die Inter-Gel-Vergleiche bei Vaterschaftsuntersuchungen wurden etabliert. Die Frequenz-Verteilung von HinfIverdauten DNA-Fragmenten der 5 VNTR-Systeme bei 650 unverwandten Dänen wird gezeigt und die Rohdaten sind verfügbar.

DNA profiles of chimeric twins, TS and MR using the single-locus-probe technique

A pair of blood-group-chimeric twins, TS and MR and their family have been investigated with the single-locus-probe DNA technique for restriction fragment length polymorphism in five variable-numbers-of-tandem-repeat systems. An admixture of DNA from the other twin could be demonstrated in both twins, leading to a possible false-genotype determination in at least one system. Chimerism is a potential pitfall in DNA investigations with single-locus probes in forensic genetics.

A Study of the Linkage Relations of Epidermolysis bullosa dystrophica

Two large families from the Faroe Islands presenting epidermolysis bullosa of the dystrophic type were subjected to extensive linkage analyses with 22 serological markers. No significant evidence in support of linkage with any of these loci was provided. It was found to be very unlikely that the gene or genes causing the present types of epidermolysis bullosa belong to the EBS1 locus known to be closely linked to the GPT locus.

HLA-GLO Linkage Analysis in 57 Informative Families

The HLA-GLO linkage relationship was investigated among 37 single backcross families with 97 children and 20 double intercross families with 51 children. For the total number of families the value Zmas = 14.600 for theta = 0.060 was found. A total of 11 cross-overs between HLA and GLO were found leading to a recombination fraction of 0.067. 221 unrelated haplotypes were examined for linkage disequilibrium between HLA and GLO, and no disequilibrium was found.

Matching Criteria for Paternity Testing with VNTR Systems

The variability in duplicate testings and in mother/child comparisons of RFLP VNTR data for paternity testing was analyzed. HinfI digested DNA was separated by electrophoresis in agarose gels and hybridized with radiolabelled probes detecting the VNTR-systems D7S22 (g3), D5S43 (MS8), D7S21 (MS31), D12S11 (MS43), and D2S44 (YNH24). The band positions on autoradiographs were measured with a ruler with 0.5 mm resolution. Initial analyses demonstrated that, when the samples which should be compared were investigated on the same gel, the absolute difference in migration distance was the parameter with the lowest variability. Comparisons of 445 duplicate investigations on the same gel of DNA from 108 individuals showed no differences exceeding 1.25 mm. This matching criterion was used for the comparisons of 1,012 differences in 215 mother-child pairs. All mother-child differences were less than 1.25 mm except for an assumed mutation in D7S21 (MS31), and this matching criterion has been chosen for the evaluation of Danish paternity cases. The allele distributions of the five VNTR systems in 530 unrelated Danes are presented.

Paternity Testing with DNA Systems: Application of D1S80 Phenotyping to Danish Paternity Cases Analysed with Five VNTR Single Locus Systems

This study presents the results of examination with D1S80 (MTC118) in 61 Danish cases of disputed paternity involving 74 men. The calculations were based on 372 unrelated Danes. The exclusion efficiency of the system D1S80 has been compared with the efficiency of the VNTR single locus systems D2S44 (YNH24), D5S43 (MS8), D7S21 (MS31), D7S22 (g3), and D12S11 (MS43a).

Paternity Testing with Five VNTR Systems in Danes

This study presents the results of examinations with five VNTR systems in Danish paternity cases. The efficiency of the five systems, the reliability of exclusions, and the mutation rates of the systems have been examined. The linkage relationship between the systems D7S21 and D7S22 has been investigated through family studies.