Thesis (M.Sc.)--Chulalongkorn University, 2005

Short tandem repeat (STR) is valuable tool in Forensic Medicine for identification of individuals. Detailed statistics of each STR allele information is unique among each ethnic group. Frequency of each STR loci is needed for calculation of probability of match and has not been determined in a large scale in Thai population. It is not known whether STR loci may be able to identify people from each geographical region. DNA from buccal swab from 1000 non-related Thais; 200 from each region: Northern, North-eastern, Eastern, Southern and Central of Thailand, were collected for PCR amplification of 16 STR loci, D8S1179, D21S11, D7S820, CSF1P0, D3S1358, THO1, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, Amelogenin, D5S818 and FGA, using AmpFlSTR Identifiler[superscript TM] kit. Automated 3100 DNA sequencer was used to analyze STR alleles using GeneMapper ID V3.2. The results show difference of DNA fingerprint among the 1000 subject. The range ofpower of discrimination of STR is 0.794-0.971. The range of matching probability is 0.029-0.206. The range of polymorphic information content (PIC) is 0.55-0.86. The range power of exclusion is 0.286-0.753. The typical paternal index is 1.24-4.13. The heterozygosity is 59.6-87.6%. Hence all studied STR loci show variety and can be applied for identification of person and parent-and-child relationship. The chance of identify identical person using AmpFlSTR Identifiler[superscript TM] kit is 1 in 2.87 x 10[superscript 17]. There is no distinctive pattern of any STR marker for people from each region of Thailand.