Simple Quantification and DNA Profiling from Degraded Low Copy Number DNA Samples

Shin, Kyoung Jin; Yoo, Ji Eun; Chung, Ukhee; Park, Myung Jin; Lee, Hwan Young; Kang, Seung Chul; Lee, Ho; Cho, Sang Ho; Kim, Chong Youl

Abstract

DNA quantification is important to ensure the consistency and the reliability in the interpretation of degraded low copy number DNA typing. We applied the simple PCR quantification method using fluo-rescently labeled primers for the amplification of mtDNA and amelogenin gene in 50 year old skeletal remains (e.g. bone and tooth). K562 DNA was serially diluted and used as a standard for concentration marker to gauge the amount of DNA from PCR versus the peak area. The quantities of DNA extracted from bones and teeth did not show significant difference in the analyses both using mtDNA and amelo-genin gene as an amplification target. To test the efficiency of DNA profiling of degraded low copy number DNA samples, mtDNA PCR quality evaluation and DNA typing for 16 autosomal STR and 9 Y chromosomal STR loci were per-formed and the correlation between DNA quantities and PCR amplification efficiencies of the samples was analyzed. The DNA quantities assayed by the simple method suggested in the present study could be good indicator for mtDNA and STR analysis. As the allele drop-out was observed in less than 0.050ng DNA samples, at least 0.100ng of DNA is required to produce informative STR profiles. Also, STRs with less than 200bp amplification sizes produce efficient DNA profiles in most cases. Therefore, the develop-ment of mini-STRs with less than 200bp amplification sizes is expected to improve DNA typing in degraded low copy number DNA. Y-STRs are easy to detect allele drop-out or drop-in, and accordingly the efficiency test of Y-STRs as well as autosomal STRs for profiling of degraded low copy number DNA samples is thought to be important.