Biological kinship investigation on critical samples: usefulness in cases of historical, archaeological or forensic investigation.

There are many cases where the establishment of a biological kinship between evidences is crucial, in a forensic, archaeological and / or historical level. The analysis of reduced size autosomal markers has proven to be effective in solving some cases with critical and degraded samples. However, there are
situations where this study is not conclusive, since autosomal unlinked markers are unable to distinguish some pedigrees (such as grandparent, avuncular and half-siblings) – the obtained likelihood
ratios between distinct hypotheses are not different from 1.
Theoretically, X-short tandem repeats (X-STRs) analysis should allow the distinction of some of those pedigrees. However, current X-chromosome commercial kits are not designed and suitable for studying critical samples, due to their DNA fragmentation and molecular degradation. So, this Project aims to provide information for the implementation and improvement of techniques in the field of critical DNA. Specifically, it is intended to develop and test specific X-chromosome markers, especially conceived for critical samples. To perform so, it is mandatory the development of a population specific
allelic and / or haplotipic database, so it could be possible to compute probabilities and to indicate the
identity or kinship likelihood ratio.