Bone sampling criteria for DNA genotyping: macroscopic sample categorization and STR typing results

Abstract

The Argentine Forensic Anthropology Team (EAAF) investigates human rights violations which took place in Argentina during the military government that ruled out from 1976 to 1983 and also cooperates in other countries with humanitarian crisis as well. Most of the bone remains that the EAAF analyses show long post mortem interval. Consequently, the skeletal remains may have been exposed to different conditions such as moisture, temperature and pH conditions, microorganisms and different types of soil that can produce various degrees of preservation. On the other hand, severely burnt remains can make the genetic analysis more complex. All the above mentioned influences the DNA quantity and quality. In the present study, we scored the samples to investigate the correlation between the bone macroscopic aspect and the concentration of the DNA extracted from it. Samples were classified into four major groups: score 1 was assigned to samples with very good preservation, score 2 to those showing slight superficial alterations. Score 3 and 4 samples showed regular and bad macroscopic appearance, respectively. Our results clearly supports that samples with good preservation show high well-preserved DNA concentrations and also a higher number of reportable STR markers in comparison to those ranked in the worst categories. This work proposes a useful guide that can help anthropologists to make a more efficient selection of aged-samples for genetic studies.