•••quote:•••Originally posted by Forensic Chick:
•I have a term paper on mitochondrial DNA and its forensic uses - however due to the fact that the concept is so new I've been unable to find any information on it (besides the textbook info on what mDNA is)... Any info would be greatly appreciated!!
-Forensic Chick-•••••This may help.
Mitochondrial DNA Analysis. Mitochondrial DNA (mtDNA) typing is increasingly used in human identity testing when biological evidence may be degraded, when quantities of the samples in question are limited, or when nuclear DNA typing is not an option. Biological sources of mtDNA include hairs, bones, and teeth. In humans, mtDNA is inherited strictly from the mother. Consequently, mtDNA analysis cannot discriminate between maternally related individuals (e.g., mother and daughter, brother and sister). However, this unique characteristic of mtDNA is beneficial for missing person cases when mtDNA samples can be compared to samples provided by the maternal relative of the missing person.
For humans, the mtDNA genome is approximately 16,000 bases (A, T, G, and C) in length containing a "control region" with two highly polymorphic regions. These two regions, termed Hypervariable Region I (HV1) and Hypervariable Region II (HV2), are 342 and 268 base pairs (bp) in length, respectively, and are highly variable within the human population. This sequence (the specific order of bases along a DNA strand) variability in either region provides an attractive target for forensic identification studies. Moreover, since human cells contain several hundred copies of mtDNA, substantially more template DNA is available for amplification than nuclear DNA.
Mitochondrial DNA typing begins with the extraction of mtDNA followed by PCR amplification of the hypervariable regions. The amplified mtDNA is purified, subjected to sequencing (Sanger et al., 1977. PNAS 74: 5463-5467), with the final products containing a fluorescently labeled base at the end position. The products from the sequencing reaction are separated, based on their length, by gel electrophoresis. The resulting sequences or profiles are then compared to sequences of a known reference sample to determine differences and similarities between samples. Samples are not excluded as originating from the same source if each base (A, T, G, or C) at every position along the hypervariable regions are similar. However, due to the size of the mtDNA database and to the unknown number of mtDNA sequences in the human population a reliable frequency estimate is not provided. Consequently, mtDNA sequencing is becoming known as an exclusionary tool as well as a technique to complement other human identification procedures.
Thank you so much! I'll be sure to check the Cal library for those articles.
