Maternal Genetic Fingerprints: An Examnation of the Science Underlying Mitochondrial DNA and Relevant Legal Cases

In most forensic cases, it is assumed that the reader knows that the deoxyribonucleic acid (DNA) mentioned is nuclear DNA; the genetic blueprint of life that can distinguish between all individuals except identical twins. In actuality, there are two types ofDNA. The other category is mitochondria1 DNA (mtDNA), which can only be used to differentiate maternal relatives. This second type of DNA is extremely useful due to its high copy number, enhanced stability, and maternal inheritance. However, laboratories that perform this type of analysis must be conscientious due to the extreme sensitivity and precision of the test. Unfortunately, there are only six laboratories in the world that currently are able to perform human mtDNA analysis for law cases due to the high cost involved. Recently there has been an increase in the number of forensic cases in which mtDNA evidence has been used. The first case in which this type of evidence obtained recognition was in the identification of the Romanov family. A new scientific development called heteroplasmy (base insertions, deletions, or replacements) was discovered in the mtDNA sequence of Czar Nicholas 11. Therefore, his brother\u27s body needed to be exhumed in order to obtain a clear match and finally settle the identity of Czar Nicholas Romanov. Another new advancement, the supposition that the maternal genetic fingerprint may also be partly paternally inherited, has caused the scientific community to reconsider the mtDNA sequence first discovered by Anderson et al. in 198 1. There have been a total of six human cases in the United States, beginning in 1996, in which mtDNA has been used to obtain convictions. In Canada, there has been only one human case, R. v. Mumin, which has involved mtDNA evidence. However, this case did not result in a conviction, event though the fingerprint matched with over 99% accuracy, due to other mitigating factors, which may have had some impact upon the verdict of not guilty