Calculation of Likelihood Ratio for Identifying Half Sibling Relationship When Both Biological Mothers Participate / 法医学杂志

Objective To derive the formulae for likelihood ratio （LR） calculation of half sibling relationships when both mothers participate. Methods Based on the fact that both biological mothers participate in the identification of half sibling relationship between the two individuals, test hypothesis for the identification of half sibling relationship was established. Conditional probability ratios of genetic evidence under null hypothesis and alternative hypothesis conditions were simplified, and then applied to a real case of half sibling relationship identification. At the same time, the LR of half sibling relationships under the assumption that only a single biological mother or none of the biological mothers participate were respectively calculated. Results In the cases of identification of half sibling relationship from same fathers, with no biological father involved, after the same genetic indicator test analysis, when both biological mothers participate in the identification, the accumulated LR value was higher than that of accumulated LR with only a single biological mother or no parents participating. Conclusion When the autosome STR test is used for the identification and analysis of half sibling relationship between two individuals, the calculation of LR is more simple, intuitive and operable with both mothers participating. The biological mothers should participate in the test as much as possible, otherwise the number of STR loci would need to be increased for a more specific conclusion.

Mutations in a Large Pedigree with Y-STR Genetic Markers / 法医学杂志

OBJECTIVE@#To explore the mutation of Y-STR loci in meiotic allelic transmission in a large pedigree.@*METHODS@#The oral swabs of 163 male individuals were collected from a Lin pedigree. Twenty-two Y-STR genetic markers were typed with AGCU Y24 fluorescent detection kit (AGCU Y24 system), which also contained 16 Y-STR markers included in Yfiler multiple amplification kit (Yfiler system). The genotyping results of Y-STR loci were compared between each two males in the pedigree.@*RESULTS@#There were 20 and 30 kinds of haplotypes obtained with Yfiler and AGCU Y24 systems in 163 male individuals from the Lin pedigree, respectively. The rates referred to haplotype differences (RRHD) of these two typing systems between male pairs were 0.910 5 and 0.922 7, respectively. The average number of marker differences were 6.582 1 and 9.824 8, respectively. The RRHD increased along with the incidents of meiosis.@*CONCLUSION@#Y-STR mutation leads to different Y-STR haplotypes among the male members in a paternal pedigree and the rate of difference increases along with the incidents of meiosis.

Age estimation using content of sjTREC in human peripheral blood / 法医学杂志

OBJECTIVE@#To determine and verify the correlation formula of age estimation using the content of signal joint T-cell receptor excision DNA circle (sjTREC) in human peripheral blood and to discuss its application value in forensic biological practice.@*METHODS@#The samples of peripheral blood stains were collected from 30 healthy unrelated individuals whose ages were known. The DNAs were extracted from the samples stored at room temperature after 4 weeks. The content of sjTREC was measured by real-time fluorescent quantitative PCR technique, and the TATA box binding protein (TBP) was selected as reference genes. The age of each sample was predicted with the formula which was Age = -7.181 5 Y-42.458 +/- 9.42 (Y = dCtTBP-sjTREC), and the result was compared with the real age of each individual to determine the accuracy of the formula.@*RESULTS@#sjTREC and TBP gene were detectable in all 30 samples of peripheral blood. The contents of sjTREC in human peripheral blood showed a decreasing tendency with aging. The accuracy rate for the age estimation by this method was 76.67%.@*CONCLUSION@#The method for the age estimation with the content of sjTREC was simple, fast, sensitive, and good species specific with important potential application prospect.

Calculation of the avuncular index / 法医学杂志

OBJECTIVE@#To introduce the method of avuncular index (AI) calculation.@*METHODS@#Identity by decent coefficient, coancestry coefficient and AI law were employed in identification of uncle-niece relationship, when autosomal STR loci were detected to determine controversial uncle-niece relationship.@*RESULTS@#The results of AI calculation were coincidental using identity by descent coefficien, coancestry coefficient and AI law.@*CONCLUSION@#The results are coincidental using three methods in the different situations. AI index is higher with participation of children's mother.

Cloning of Rcet3, a novel gene related to family 2 cystatins / 南方医科大学学报

<p><b>OBJECTIVE</b>To clone the full-length Rcet3 gene, a novel gene related to family 2 cystatins, from mouse testis or other tissues.</p><p><b>METHODS</b>Rcet3 gene was cloned using digital differential display (DDD) and RT-PCR was performed for cloning the full-length Rcet3 gene from adult mouse testis cDNA library with sequence analysis.</p><p><b>RESULTS</b>Rcet3 cDNA was 610 bp in length, consisting of 4 exons to encode a protein with 140 amino acid residues. The encoded protein contained a potential signal peptide and a cystatin domain, but lacked critical consensus site important for cysteine protease inhibition. These characteristics could be seen in the Cres subgroup related to the family 2 cystatins. Rcet3 was specifically expressed in adult mouse testis, epididymis and the cerebrum, but at higher levels in the testis than in the epididymis and cerebrum.</p><p><b>CONCLUSION</b>Rcet3 may be a new member of Cres subgroup of family 2 cystatins.</p>