Relationship between PMI and ATR-FTIR Spectral Changes in Swine Costal Cartilages and Ribs / 法医学杂志

OBJECTIVE@#To analyze postmortem chemical changes in Landrace costal cartilages and ribs using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and to provide a novel technique for estimation of postmortem interval (PMI).@*METHODS@#The swines were sacrificed by hemorrhage and their costal cartilages and ribs were kept in 20 degrees C. The chemical analysis of the costal cartilages and ribs were performed using ATR-FTIR every 72 h. The correlation between the certain spectral parameters and PMI was also analyzed. The time-dependent changes of costal cartilages were more significant than ribs.@*RESULTS@#There were no obvious changes for the main absorbance bands position, and some absorbance band ratios showed time-dependent changes and significant correlations with the PMI.@*CONCLUSION@#ATR-FTIR has the ability to analyze postmortem chemical changes of the swine costal cartilages and ribs, and it can be a new method to estimate PMI based on spectroscopy.

Calculation of likelihood ratio for X-STR typing in kinship testing / 法医学杂志

OBJECTIVE@#To deduce the calculation formulae of likelihood ratio for kinship testing with X-short tandem repeat (X-STR) typing.@*METHODS@#With the identity by decent coefficient of different relationships, the joint genotypic probability of two individuals with specific genotypes was calculated as X value, and then the joint genotypic probability of two unrelated individuals was calculated as Y value; therefore, the likelihood ratio value (X/Y) was obtained.@*RESULTS@#The calculation formulae of the likelihood ratio for different genotype combinations of the female-female, female-male and male-male genetic relationships were derived and verified by real cases.@*CONCLUSION@#The calculation formulae are simple and accurate to evaluate the likelihood ratio for two individuals' genetic relationship with X-STR typing. The formulae provide the basic potential value for the difficult kinship testing with X-STR loci.

Analysis of allelic drop-out at short tandem repeat loci / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the cause for allelic drop-out at short tandem repeat (STR) loci upon paternity testing with a PowerPlex® 16 kit.</p><p><b>METHODS</b>A total of 10 642 DNA confirmed paternity testing cases (18 314 parent/child allelic transfers) were analyzed with the PowerPlex® 16 kit. Samples suspected for having allelic drop-out were verified with an Identifiler™ kit and/or locus-specific singleplex amplification systems. PCR products of null alleles were separated and directly sequenced.</p><p><b>RESULTS</b>Eight cases of allelic drop-out were found. The overall rate of null allele in the PowerPlex® 16 system was 0.437 × 10(-3). DNA sequencing has confirmed single base variations within the binding region of published primers, in which 4 cases involved the D18S51 locus (2 cases with G>A transitions at 79 bp upstream of the repeats, 1 case with G>T transversion at 162 bp downstream of the repeats and 1 case with G>C transversion at 74 bp upstream of the repeats), 2 cases involved the D21S11 locus (1 case with C>A transversion at 17 bp upstream of the repeats and 1 case with A>G transition at 12 bp upstream of the repeats). One case involved the FGA locus (1 case with G>A transition at 142 bp downstream of the repeats) and 1 case involved TPOX locus (1 case with G>A transition at 198 bp downstream of the repeats).</p><p><b>CONCLUSION</b>Base variation in the primer binding region may cause failed PCR and result in null allele reports. Alternative primer sets should be used to verify the suspected allelic drop-out. Attention should be paid to this during paternity testing and data exchange for personal identification.</p>