ethods used to determine the identity of the skeletal remains, and whether they were in fact the lost Romanov family, including Tsarevich Alexei (the royal heir) and one of his sisters.
‘We report forensic DNA testing on the remains discovered in 2007 using mitochondrial DNA (mtDNA), autosomal STR, and Y-STR testing.’ This line from the examining officers’ report shows the tests used. (PubMed, 2009) A brief description of each will show how the team came to their conclusion.
A person’s mother-line ancestry can be determined with mitochondrial DNA testing. Mitochondrial DNA (mtDNA) is a type of DNA that is carried by both men and women but is only inherited from their mother. It is passed by a mother down to all her children. An exact match might mean the tested person is very likely to share a common maternal ancestor within the last 500 years. Exact matches are rare, but slight differences (one or two) can also lead to decisions about common relatives on the mother’s side.(Sorensen, 2009) The testing is done by sequencing nucleotides. The Romanov gravesite skeletons were tested in this way.
Autosomal STR testing examines Short Tandem Repeats, using the knowledge that most humans share about 99 percent of their DNA, while the rest is very different. This small portion is examined because, although its function in the body is not completely understood yet, it provides a high degree of variation that can be measured and compared. (Orchid Cellmark 2009)
These sequences repeat a number of times - between six and 40 - in a particular location on the DNA. For example, ACGTACGTACGTACGTACGTACGT. Each person can have a different number of repeats in the same place. Many STRs occur on each chromosome. One subset has been developed for identity testing purposes. (Orchid Cellmark Ibid). This was used in the Romanov case, and helped the scientists decide the relationship between the skeletons and that they belonged to one family.
Y-STR testing is done on the