| Summary: | 碩士 === 臺中健康暨管理學院 === 生物科技學系碩士班 === 94 === Abstract
In the human genome, there are some repetitive and polymorphic short base DNA fragments called Short Tandem Repeats (STRs), which can be used as markers for polymorphic analyses. Through Polymerase Chain Reaction, a sufficient amount of products can be generated by repeating the specific DNA fragments. Subsequently, using Capillary Electrophoresis (usually through the ABI Genescan system), the alleles are separated according to the lengths of the DNA fragments. By identifying the variations in the number of repetitive DNA fragments, the relationships between samples back-check, i.e. whether they share the same genetic source or if there is a family connection, can be determined. The versatile nature of polymorphism in the STRs has enabled it to be extensively used in both forensic identifications and parental testing. A number of statistical parameters, including Power of Discrimination, Homozygosis Values, Matching Probability, Power of Exclusion and Paternity Index, are considered as important references. The value of PI and its educated guess value are of great importance in confirming whether there is a parental relationship between the two tested parties.
This study is focusing on the cross-analyses of the variations in the PI of the related confirmed by their parents, and those not. In addition, it aims to foster the discussion on how to determine the PI value. Twenty-seven groups, a total number of sixty-four people who are thought to have kinships, have taken part in this research. It is found that, by using 15 STR, the kinships among participants are correctly identified. However, when these people are randomly allocated for matching, with CPI values below 1,000, there are only four groups that have reached 99.9%, which is below the National Standard of 99.99%. On the other hand, a mutation in the DNA has been found in two children. If we were to run the test following the old method, we would most likely to reject the possibility of kinship. As a result, this research has a particular emphasis on paying attention to the possibility of DNA mutation in the Paternity Excluded Testing to avoid mistakes.
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