Population data for 17 Y-chromosome STRs in a sample from Apulia (Southern Italy)

The 17 Y-STR loci included in the AmpFLSTR Yfiler PCR Amplification Kit were analyzed in 98 unrelated healthy males from Apulia (Southern Italy). A total of 97 different haplotypes were identified, of which 96 haplotypes were unique and 1 occurred twice. Allele frequencies for each Y-STR locus in pooled sample and estimated value of gene diversity (GD) were evaluated. The lowest value of GD was observed for DYS392 (0.126) and the highest one (0.936) for DYS385. The HD (haplotype diversity) for the studied Y-STR set showed a value of 0.9994, with an HMP (haplotype match probability) value of 0.0006, while the overall DC was 98.98%. Microvariant alleles were found for the DYS458 and DYS385 markers and sequenced. Furthermore, Φst-based genetic distance computation and pair-wise analysis of molecular variance (AMOVA) test were carried out. When comparing our population with the Apulia sample previously investigated, the AMOVA analysis detected no evidence for significant differentiation. The comparison with all Italian populations submitted to the YHRD website showed no relevant differences with all Southern Italian populations (San Giorgio La Molara, Belvedere, Trapani and Catania) and significant genetic deviation with all Northern Italian populations (Udine, Biella, La Spezia, Modena, Ravenna, Marche and North Sardinia). Moreover, the other populations and meta-populations belonging to the whole Mediterranean area (Croatia, Macedonia, Albania, Greece, Turkey, Israel, Libya, Tunisia, Algeria, Morocco and Spain) were different from our Apulia sample. The data were submitted to YHRD

Population data for 17 Y-chromosome STRs in a sample from Apulia (Southern Italy)

The 17 Y-STR loci included in the AmpFLSTR Yfiler PCR Amplification Kit were analyzed in 98 unrelated healthy males from Apulia (Southern Italy). A total of 97 different haplotypes were identified, of which 96 haplotypes were unique and 1 occurred twice. Allele frequencies for each Y-STR locus in pooled sample and estimated value of gene diversity (GD) were evaluated. The lowest value of GD was observed for DYS392 (0.126) and the highest one (0.936) for DYS385. The HD (haplotype diversity) for the studied Y-STR set showed a value of 0.9994, with an HMP (haplotype match probability) value of 0.0006, while the overall DC was 98.98%. Microvariant alleles were found for the DYS458 and DYS385 markers and sequenced. Furthermore, Φ st-based genetic distance computation and pair-wise analysis of molecular variance (AMOVA) test were carried out. When comparing our population with the Apulia sample previously investigated, the AMOVA analysis detected no evidence for significant differentiation. The comparison with all Italian populations submitted to the YHRD website showed no relevant differences with all Southern Italian populations (San Giorgio La Molara, Belvedere, Trapani and Catania) and significant genetic deviation with all Northern Italian populations (Udine, Biella, La Spezia, Modena, Ravenna, Marche and North Sardinia). Moreover, the other populations and meta-populations belonging to the whole Mediterranean area (Croatia, Macedonia, Albania, Greece, Turkey, Israel, Libya, Tunisia, Algeria, Morocco and Spain) were different from our Apulia sample. The data were submitted to YHRD

The molecular characterisation of a depurinated trial dna sample can be a model to understand the reliability of the results in forensic genetics

35siThe role of DNA damage in PCR processivity/fidelity is a relevant topic in molecular investigation of aged/forensic samples. In order to reproduce one of the most common lesions occurring in post mortem tissues, a new protocol based in aqueous hydrolysis of the DNA was developed in vitro. Twenty five forensic laboratories were then provided with 3.0 µg of a trial sample (TS) exhibiting, in mean, the loss of 1 base out of 20, and a molecular weight below 300 bp. Each participating laboratory could freely choose any combination of methods, leading to the quantification and to the definition of the STR profile of the TS, through the documentation of each step of the analytical approaches selected. The results of the TS quantification by qPCR showed significant differences in the amount of DNA recorded by the participating laboratories using different commercial kits. This data shows that only DNA quantification “relative“ to the used kit (probe) is possible, being the “absolute” amount of DNA inversely related to the length of the target region (r2=0.891). In addition, our results indicate that the absence of a shared stable and certified reference quantitative standard is also likely involved. STR profiling was carried out selecting five different commercial kits and amplifying the TS for a total number of 212 multiplex PCRs, thus representing an interesting overview of the different analytical protocols used by the participating laboratories. Nine laboratories decided to characterise the TS using a single kit, with a number of amplifications varying from 2 to 12, obtaining only partial STR profiles. Most of the participants determined partial or full profiles using a combination of two or more kits, and a number of amplifications varying from 2 to 27. The performance of each laboratory was described in terms of number of correctly characterised loci, dropped out markers, unreliable genotypes and incorrect results. The incidence of unreliable and incorrect genotypes was found to be higher for participants carrying out a limited number of amplifications, insufficient to define the correct genotypes from damaged DNA samples such as the TS. Finally, from a dataset containing about 4,500 amplicons, the frequency of PCR artefacts (allele drop out, allele drop in and allelic imbalance) was calculated for each kit showing that the new chemistry of the kits is not able to overcome the concern of template-related factors. The results of this collaborative exercise emphasize the advantages of using a standardized degraded DNA sample in the definition of which analytical parameters are critical for the outcome of the STR profiles.reservedmixedFattorini P; Previdere C; Sorçaburu-Cigliero S; Marrubini G; Alù M; Barbaro A; Carnevali E; Carracedo A; Casarino L; Consoloni L; Corato S; Domenici R; Fabbri M; Giardina E; Grignani P; Baldassarra SL; Moratti M; Pelotti S; Piccinini A; Pitacco P; Plizza L; Resta N; Ricci U; Robino C; Salvaderi L; Scarnicci F; Schneider PM; Seidita G; Trizzino L; Turchi C; Turrina S; Vatta P; Vecchiotti C; Verzeletti A; De Stefano F.Fattorini, P; Previdere, C; Sorçaburu Cigliero, S; Marrubini, G; Alù, M; Barbaro, A; Carnevali, E; Carracedo, A; Casarino, L; Consoloni, L; Corato, S; Domenici, R; Fabbri, M; Giardina, E; Grignani, P; Baldassarra, Sl; Moratti, M; Pelotti, S; Piccinini, A; Pitacco, P; Plizza, L; Resta, N; Ricci, U; Robino, C; Salvaderi, L; Scarnicci, F; Schneider, Pm; Seidita, G; Trizzino, L; Turchi, C; Turrina, S; Vatta, P; Vecchiotti, C; Verzeletti, Andrea; De Stefano, F

The molecular characterization of a depurinated trial DNA sample can be a model to understand the reliability of the results in forensic genetics.

The role of DNA damage in PCR processivity/fidelity is a relevant topic in molecular investigation of aged/forensic samples. In order to reproduce one of the most common lesions occurring in postmortem tissues, a new protocol based on aqueous hydrolysis of the DNA was developed in vitro. Twenty-five forensic laboratories were then provided with 3.0 μg of a trial sample (TS) exhibiting, in mean, the loss of 1 base of 20, and a molecular weight below 300 bp. Each participating laboratory could freely choose any combination of methods, leading to the quantification and to the definition of the STR profile of the TS, through the documentation of each step of the analytical approaches selected. The results of the TS quantification by qPCR showed significant differences in the amount of DNA recorded by the participating laboratories using different commercial kits. These data show that only DNA quantification "relative" to the used kit (probe) is possible, being the "absolute" amount of DNA inversely related to the length of the target region (r2 = 0.891). In addition, our results indicate that the absence of a shared stable and certified reference quantitative standard is also likely involved. STR profiling was carried out selecting five different commercial kits and amplifying the TS for a total number of 212 multiplex PCRs, thus representing an interesting overview of the different analytical protocols used by the participating laboratories. Nine laboratories decided to characterize the TS using a single kit, with a number of amplifications varying from 2 to 12, obtaining only partial STR profiles. Most of the participants determined partial or full profiles using a combination of two or more kits, and a number of amplifications varying from 2 to 27. The performance of each laboratory was described in terms of number of correctly characterized loci, dropped-out markers, unreliable genotypes, and incorrect results. The incidence of unreliable and incorrect genotypes was found to be higher for participants carrying out a limited number of amplifications, insufficient to define the correct genotypes from damaged DNA samples such as the TS. Finally, from a dataset containing about 4500 amplicons, the frequency of PCR artifacts (allele dropout, allele drop-in, and allelic imbalance) was calculated for each kit showing that the new chemistry of the kits is not able to overcome the concern of template-related factors. The results of this collaborative exercise emphasize the advantages of using a standardized degraded DNA sample in the definition of which analytical parameters are critical for the outcome of the STR profiles

A global analysis of Y-chromosomal haplotype diversity for 23 STR loci

In a worldwide collaborative effort, 19,630 Y-chromosomes were sampled from 129 different populations in 51 countries. These chromosomes were typed for 23 short-tandem repeat (STR) loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385ab, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, GATAH4, DYS481, DYS533, DYS549, DYS570, DYS576, and DYS643) and using the PowerPlex Y23 System (PPY23, Promega Corporation, Madison, WI). Locus-specific allelic spectra of these markers were determined and a consistently high level of allelic diversity was observed. A considerable number of null, duplicate and off-ladder alleles were revealed. Standard single-locus and haplotype-based parameters were calculated and compared between subsets of Y-STR markers established for forensic casework. The PPY23 marker set provides substantially stronger discriminatory power than other available kits but at the same time reveals the same general patterns of population structure as other marker sets. A strong correlation was observed between the number of Y-STRs included in a marker set and some of the forensic parameters under study. Interestingly a weak but consistent trend toward smaller genetic distances resulting from larger numbers of markers became apparent