STR analysis of artificially degraded DNA-results of a collaborative European exercise

Degradation of human DNA extracted from forensic stains is, in most cases, the result of a natural process due to the exposure of the stain samples to the environment. Experiences with degraded DNA from casework samples show that every sample may exhibit different properties in this respect, and that it is difficult to systematically assess the performance of routinely used typing systems for the analysis of degraded DNA samples. Using a batch of artificially degraded DNA with an average fragment size of approx. 200 bp a collaborative exercise was carried out among 38 forensic laboratories from 17 European countries. The results were assessed according to correct allele detection, peak height and balance as well as the occurrence of artefacts. A number of common problems were identified based on these results such as strong peak imbalance in heterozygous genotypes for the larger short tandem repeat (STR) fragments after increased PCR cycle numbers, artefact signals and allelic drop-out. Based on the observations, strategies are discussed to overcome these problems. The strategies include careful balancing of the amount of template DNA and the PCR cycle numbers, the reaction volume and the amount of Taq polymerase. Furthermore, a careful evaluation of the results of the fragment analysis and of automated allele calling is necessary to identify the correct alleles and avoid artefacts.     

Radiologically determined DMF index variations for forensic age estimation of young adults

The eruption and mineralization of third molars are the main criteria for dental age estimation of living people involved in criminal proceedings. Since the development of third molars is usually completed by the age of 19 or 20 years, this feature cannot be used to ascertain whether a person has attained the forensically relevant age of 21 years. This study examined whether the DMFT index or the third molar DFT index could supply reliable information enabling conclusions to be drawn about whether a person has reached the age of 21. To this end, 650 conventional orthopantomograms of German subjects aged 18 to 30 years were evaluated. The DMF index variations considered were found to be unsuitable for determining whether a person is over 21 because they displayed a weak correlation with age and considerable individual scatter. A high indicative value can only be attributed to a third molar DFT index of 4, although this is rarely observed in the relevant age group. An X-ray examination of the medial clavicular epiphyseal cartilage is, therefore, strongly recommended when assessing whether a person has attained 21 years of age.     

Suicide risk in outpatients with specific mood and anxiety disorders

The present study examined the relationships between specific anxiety, mood disorders, levels of hopelessness, and suicide ideation. The sample consisted of 606 outpatients recruited from several psychiatric settings. It was found that dysthymia was significantly associated with hopelessness. Patients presenting major depressive episode with higher anxiety symptoms had significantly increased scores on the hopelessness scale. Major depressive episode and bipolar disorder, but not dysthymia, were significantly associated with higher levels of suicide ideation. Increased levels of anxiety symptoms in patients with dysthymia were associated with increased levels of suicide ideation, while increased depressive symptoms in patients with specific phobia and generalized anxiety disorder were associated with significantly lower levels of suicide ideation. The findings suggest that depressive disorders, but not anxiety disorders, constitute risk for suicide. Moreover, the differentiation between a depressive and an anxiety disorder as the principal diagnosis, as well as the assessment of anxiety-level symptoms in patients with major depressive episode and dysthymia, seems of special relevance when assessing suicide risk.     

The latin american business environment: patent protection issues

Considers the issue of patent rights in Argentina, Brazil, Chile, and Mexico. Reviews both theoretical and empirical literature on fitting patent systems to national circumstances. Data are considered shedding light on trade flows and capital formation, two areas impacted by strong or weak protection. Recommends a general hybrid system for Latin American nations, meeting GATT standards while remaining adaptable to individual country needs.     

Two examples of null alleles at the D19S433 locus due to the same 4 bp deletion in the presumptive primer binding site of the AmpFlSTR Identifiler kit

Two cases of allelic loss at the D19S433 locus after multiplex PCR with the AmpFlSTR Identifiler kit (Applied Biosystems) are described. In both cases the failure of PCR resulted in genetic inconsistencies due to opposite homozygosity. After singleplex PCR with published primers additional alleles were observed and Mendelian inheritance was restored. These PCR products were sequenced and in both cases the same 4 bp deletion near the 3′ end of the repeat region was detected in two alleles of different length. The frequency of these null alleles (two events in 1026 allelic transfers) amounts to 0.0019 (95% confidence limits: 0.0002-0.0070).