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To introduce the method of avuncular index (AI) calculation.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.The results of AI calculation were coincidental using identity by descent coefficien, coancestry coefficient and AI law.The results are coincidental using three methods in the different situations. AI index is higher with participation of children's mother.

To introduce a new method for calculating the paternity index (PI).Assuming that each allele from parents has undergone a transition before it segregates and transmits to child. The transition probability is 1 when parent allele is the same as child's, the transition probability is 0 when parent allele is different from the child's. Every allele has a transmission probability with 0.5. Base on these theories, it is easy to gain the probability that child inherits an allele from the alleged father or mother. Thus, the X value (numerator) and Y value (denominator) of PI formula can be calculated, as unknown man provide an allele for child with the allele frequency.A general formula that calculated the PI for trios, duos and missing child cases was deduced.The new method is practical in all kinds of forensic paternity case.

To introduce a method of calculating the paternity index (PI) for autosomal codominant markers when the mutation is encountered.Assuming mutation arises with a mutational probability before an allele segregates and transmits to child with 1/2 chance, the probability of a random man giving an allele to child is the allele frequency in population. Considering only one mutation event in one case, the mutant allele can be determined by comparing the allele between parents and child. Furthermore, the probability of child's genotype can be calculated to identify the father between a tested man and a random male. Subsequently, the PI can be calculated.Formula of PI was deduced for trios, duos and missing child cases, including maternal mutation.The method is easy to understand and useful in paternity testing.

To investigate the application of ITO method and discriminant functions method in full sibling and half sibling identification.Five hundred pairs of full siblings (FS), 50 pairs of half siblings (HS) and 500 pairs of unrelated individuals (UR) were genotyped by PowerPlex 16 system. Full sibling index (FSI), half sibling index (HSI) and the FSI:HSI ratio were calculated with ITO method. Allelic matching of each pair of the three groups was compared. The locus numbers of no-allele sharing (x0), half-allele sharing (x1) and two-alleles sharing (x2) were calculated, respectively. The discriminant functions about full-siblings, half-siblings and unrelated individuals (UR) were established by SPSS 13.0 statistical software.(1) Regard FSIor = 19 or FSI1 as the standard of distinguishing full sibling from unrelated individual, the alternate correct percentage was 96.4%. Regard HSIor = 19 or HSI1 as the standard of distinguishing half sibling from unrelated individual, the alternate correct percentage was 85.3%. Regard FSI:HSIor = 1 or FSI:HSI1 as the standard of distinguishing full sibling from half sibling, the alternate correct percentage was 87.5%. (2) Four groups of discriminant functions were established. The alternate correct percentage of these discriminant functions were 84.4%-97.7%, with the highest one in full sibship-unrelated individual group.Both ITO method and discriminant functions method are efficient in identification of full sibling or half sibling.

To devise a multiplex PCR system of three X-chromosome specific short tandem repeat (X-STR) loci and study the genetic polymorphism.DXS6799, DXS6804 and DXS6854 were amplified simultaneously using a multiplex system and were typed by polyacrylamide gel electrophoresis and silver staining.A total of 262 male and 255 female individuals from Guangdong Han population were tested; each locus showed 7 alleles. 73 haplotypes were detected in the male individuals. The haplotype diversity reached 0.9674.The 3 X-STR multiplex system is relatively abundant in polymorphic information for forensic identification and paternity testing.

DXS7132 and DXS6804 were amplified by means of multiplex PCR and detected by polyacrylamide gel electrophoresis and silver stain. Population study has been carried out in Guangdong Han Population of South China. DXS7132 exhibited 7 distinguishable alleles ranging from 276-300 bp in size. Number of alleles at DXS6804 was 6 and its range was 177-201 bp. Sequencing revealed that their common sequence motifs were tetranucleotide repeats. On the genomic mapping information linkage disequilibrium between DXS7132 and DXS6804 was shown. Female haplotypes were determined by analyzing family trios. In 827(211 males, 616 females) chromosomes, total 33 haplotypes were identified. Deviation from Hardy-Weinberg equilibrium was not detected in the female diploid data. Gene diversity, polymorphism information content and probability of exclusion for the two loci were 0.9999, 0.9440 and 0.9411, respectively. Investigation in 308 family trios suggested a co-dominant X-linked inheritance and mutations were not found. The result indicates that DXS7132 and DXS7132 will be very useful for paternity testing that involve a female child, especially for the deficiency parents cases.

To obtain the genetic polymorphism data of Guangxi, Hunan, Henan, Sichuan, Taiwang Chinese Han population and compare the polymorphism of PentaD and PentaE STR locus.The two loci was analyzed by using the PowerPlex 16 System.10 alleles of PentaD and 19 alleles of PentaE were found in the five Han population. PentaD and PentaE have the expected heterozygosity values of 0.7746-0.8047 and 0.9005-0.9219, the polymorphism information content values of 0.7710-0.8025 and 0.8969-0.9176, the discrimination power values of 0.9223-0.9341 and 0.9471-0.9782, the power of exclusion values of 0.5435-0.6325 and 0.6785-0.8465, respectively.The result showed that these two loci were highly informative and suitable for forensic application.