Autosomal microsatellite data from Northwestern Colombia

Allele frequencies and some forensic parameters for 12 autosomal microsatellites (CSF1PO, TPOX, THO1, VWA, D16S539, D7S820, D13S317, D5S818, F13A1, FESFPS, F13B, LPL) were estimated from three departments from Northwestern Colombia. The total number of samples analysed was 1045 individuals. Comparative analysis among the three studied departments and with other published Colombian populations were also performed and discussed.     

Problems of assessing sibship probabilities by means of genetic analysis

Nowadays, kinship studies based only on STR analysis are a very common practice. Apart from regular paternity cases, there is a rising number of cases in which the type of sibship between two persons has to be determined. Very often the parents or further relatives are unavailable for testing, so that the probability e. g. for a half-sibship has to be calculated as a deficiency situation. 50 unrelated persons (Group 1), 50 full siblings (Group 2), and 50 half-siblings (Group 3) were genotyped using the 15 STRs comprised by the AmpFlSTR Identifiler multiplex PCR-kit to investigate the reliability of common statistics programs and the indicative value of the calculated probabilities. Using a commercially available statistics program, we calculated probabilities for the following hypotheses: 1. The persons investigated are full siblings; 2. the persons investigated are half-siblings; 3. the persons investigated are unrelated. After STR analysis, half-sibling probabilities between 0.03 %-97.56% for group 1, between 0.01%-78.46% for group 2, and between 24.28%-90.18% for group 3 were calculated. In addition, the authors present two complicated deficiency cases which could be resolved only by extensive DNA typing using X- and Y-chromosomal loci, respectively, as well as the investigation of further relatives. The results of this study suggest that typing of autosomal STRs alone is no sufficient tool for resolving cases of possible half-sibship, even if probabilities of more than 90.0% are obtained. Due to the results of our study we suggest the implementation of mandatory standards for the investigation and interpretation of complicated kinship cases.     

Possible pitfalls in motherless paternity analysis with related putative fathers

Nowadays, more and more paternity cases are carried out investigating only child and putative father, mostly for economical or private reasons. Usually, reliable results can be obtained and the putative father can be included or ruled out with a high certainty. Considerable problems might arise when a relative of the biological father is investigated as being the putative father. In this study, we investigated 164 persons from 27 families creating artificial deficiency cases using the AmpFlSTRIdentifiler kit, which amplifies 15 STRs simultaneously. We analyzed 93 child/biological father pairs and the corresponding uncles, respectively the brothers of the biological fathers. The average paternity probability for the biological father was 99.9699% (paternity index (PI): 3321.26); only in three cases the results were under 99.9%. In five out of 125 child/uncle pairs no STR mismatches were found and paternity probabilities between 99.9726% (PI 3652) and 99.9970% (PI 33,545) were calculated. The average number of excluding loci was 3.4, but in 31.2% of the cases only zero, one or two mismatches were found. When both putative fathers were genetically typed, the biological father usually had a statistically higher paternity probability. Nevertheless, the differences between probabilities for father and uncle were only small. These results show that a reliable investigation of deficiency cases (i.e. child and putative father) seems to be more difficult than generally assumed. Especially in cases with an unknown familiar background and/or when investigating foreigners for immigration purposes, the laboratory expert should include the mother, increase the number of investigated loci or include a second method such as RFLP-analysis, some serological systems or typing of X-chromosome specific STRs to further ascertain the results.     

Sourcing Brazilian marijuana by applying IRMS analysis to seized samples

The stable carbon and nitrogen isotopic ratios were measured in marijuana samples (Cannabis sativa L.) seized by the law enforcement officers in the three Brazilian production sites: Pernambuco and Bahia (the country's Northeast known as Marijuana Polygon), Pará (North or Amazon region) and Mato Grosso do Sul (Midwest). These regions are regarded as different with respect to climate and water availability, factors which impact upon the isotope fractionations of these elements within plants. It was possible to differentiate samples from the dry regions (Marijuana Polygon) from those from Mato Grosso do Sul and Pará, that present heavier rainfall. The results were in agreement with the climatic conditions of the suspected regions of origin and this demonstrates that seized samples can be used to identify the isotopic signatures of marijuana from the main producing regions in Brazil.     

Autosomal microsatellite data from Northwestern Colombia

Allele frequencies and some forensic parameters for 12 autosomal microsatellites (CSF1PO, TPOX, THO1, VWA, D16S539, D7S820, D13S317, D5S818, F13A1, FESFPS, F13B, LPL) were estimated from three departments from Northwestern Colombia. The total number of samples analysed was 1045 individuals.Comparative analysis among the three studied departments and with other published Colombian populations were also performed and discussed.