Nails as optimal source of DNA for molecular identification of 5 decomposed bodies recovered from seawater: from Y-ancestry to personal identification.

Molecular identification of extremely compromised human remains in forensic field is usually performed from DNA typing of bones, which are a difficult sample to work with. Moreover, autosomal STR profiles do not always result in the identification of the donor due to lack of comparisons or non-hit throughout database searching. An attempt to overcome these issues is represented by fingernails as an alternative DNA source and Y-STRs typing to infer both geographical and familial ancestry of the unknown donor. In this study, we analyzed both 24 autosomal and 27 Y-chromosome STRs from unidentified human remains (UHRs) of five males recovered from the water near the southwestern coast of Sardinia by the Italian Harbor Master's Office. Nail clippings provided an optimal source of autologous DNA for molecular identification in a very short time, producing complete autosomal and Y-STR profiles even under conditions of high body degradation. Unfortunately, no match neither compatibility occurred using autosomal STRs (aSTRs), initially. Upon analyzing the Y-haplotypes, we found out they had already been observed in northern Africa, providing us important investigative leads. This prompted the International Criminal Police Organization (INTERPOL) to provide us with references of alleged relatives that were then confirmed to be related. The use of fingernails represents an excellent DNA source especially for genetic identification of decomposed bodies recovered in seawater environment. Notably, DNA extracted from nails gave high-quality Y-STR haplotypes by which predicting paternal ancestry of the unidentified donors may result fundamental in the forensic investigative context.

Estimating population genetics and forensic efficiency of the GlobalFiler PCR amplification kit in the population of Sardinia (Italy).

GlobalFiler is a new PCR amplification kit that includes 21 autosomal short tandem repeats and three sex-determining loci. In the present research, for the first time, the GlobalFiler kit was tested to analyze a sample of 500 unrelated individuals from 18 villages encompassing the entire area of Sardinia (Italy). We tested if the kit, which is a powerful tool in forensic studies, may also find application in the field of population genetics. In agreement with data from the literature on forensic parameters values, marker SE33 showed the highest degree of polymorphism, whereas TPOX was the least informative locus. Seventeen out of twenty-one autosomal markers included in the kit resulted highly polymorphic, and therefore Globalfiler turned out to be highly useful for forensic analysis in the Sardinian population. Moreover, our data suggest developing different STR databases in different populations, like Sardinians, to increase the statistical power of autosomal STR profiling. On the other hand, due to the presence of some very highly polymorphic markers, the efficiency of Globalfiler in detecting geographical variability is affected. Indeed, the differentiation previously observed between the Sardinian and Italian populations appeared greatly reduced and even the presence of genetic isolates, previously recorded when uniparental markers was not revealed.

Successful analysis of a 100 years old semen stain generating a complete DNA STR profile.

We performed forensic investigations on a handkerchief containing seminal fluid deposited 100 years earlier. The aim was to verify the possibility to achieve a complete genetic profile exceeding the limit of success reached until today with a partial semen stain profile stored up to 50 years. The current forensic methods were carried out: Alternative Light Source (ALS), Prostate-Specific Antigen (PSA) Test, autosomal and Y-chromosome Short Tandem Repeats (STRs). ALS inspection was a crucial method in the success of the analysis. On a dried semen stain, fluorescence remains constant for a very long time, allowing possibility to minimize the fabric sample to analyze, in order to preserve specimen for future defense guarantees or to protect historical finding. We achieved positive results in 3 of 6 traces, PSA and DNA results were concordant, only those cuttings that tested positive for PSA yielded DNA profiles. A complete male profile was generated by AmpFlSTR Identifiler Plus and 16 loci profile by AmpFLSTR Yfiler. Considering some historical sources that attributed this handkerchief dated 1916, to a famous Italian poet, the DNA profile found on the handkerchief was compared with a living male descendant, and the comparison of the Y-STR between the two gave positive results, confirming the reliability of the outcomes. The findings achieved by the current forensic method empower the application of this methodology to other forensic cases, especially in past unresolved cases.

The successful recovery of low copy number and degraded DNA from bones exposed to seawater suitable for generating a DNA STR profile.

A universal method allowing for DNA profiling from bones exposed to seawater has not been reported yet. This study refers on the identification of a body immersed in seawater for 8 months. The biological material for identification was the mandibular body, usually characterized by low success rates of DNA analysis. Initially, two extraction protocols were performed with negative results: one used for bones immersed in fresh water and a silica-column procedure. A third protocol was performed, which combined the extraction of a higher amount of bone powder, the use of multi-silica-based extraction columns followed by a concentration step. This protocol allowed to obtain low copy number DNA and to generate a 12-loci STR profile by combining conventional STR typing and mini-STR technologies. This protocol could be suitable when human bones have been exposed to severe environmental conditions, and the available nuclear DNA is highly degraded and in low copy number.

Population data for Y-chromosome haplotypes defined by AmpFlSTR YFiler PCR amplification kit in North Sardinia (Italy).

The 17 Y-chromosomal short tandem repeats (STRs) included in the AmpFlSTR YFiler Amplification Kit (AB Applied Biosystems) (DYS19, DYS3891, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635 and GATA H4.1) were typed in 100 samples from North Sardinia (Italy). A total of 91 different haplotypes were found, where 9 haplotypes were shared by two individuals. The overall haplotype diversity (HD) was 0.9982. DYS458 non-consensus alleles were found in one samples, and one in the DYS438. We found a double peak in one sample for the DYS19 with alleles 15/16. Population comparisons with available 10 YSTR loci data in Mediterranean Basin samples were undertaken, significant differences were observed between our sample and all the compared populations, except for a entire sample from Sardinia. Prediction of haplogroups showed I2al was found to be the most frequent haplogroup (33%) in our sample. Testing high-resolution Y-chromosome data sets it is useful in autochthonous population and micro-population studies to highlight the most informative loci for evolutionary aims.