Daily Archives: August 5, 2009

Mitochondrial DNA and the Heart of a Future King

Everyone knows the story of King Louis XVI and Marie Antoinette. Yanked from the throne during the French Revolution, King Louis was beheaded on January 21, 1793. Marie, after her famous “let them eat cake” statement, followed her husband to the guillotine at present-day Place de la Concorde some 10 months later on October 16th. But what of their son Louis Charles?

Louis Charles

After the revolution, loyal royalist proclaimed that Louis Charles, also known as The Dauphin, would one day be King Louis XVII, an actthat made him a threat to the Revolution. In July 1793, he was taken kicking and screaming from his mother Marie and placed in the Temple prison, where he was held in solitary confinement. He was eight years old at the time. He apparently became ill with a form of TB and suffered severe psychological damage from lack of human contact. He died in 1795 at the age of 10.

Almost immediately rumors began to circulate that the young future King had escaped to the countryside. This was not the case but that did not stop the rumors.

An autopsy was performed on Charles Louis by French physician Philippe-Jean Pelletan. Apparently he removed Louis’ heart and preserved it in alcohol. Once the alcohol evaporated, the heart dried out and became mummified. The heart was then stolen by one of Pelletan’s students, who many years later made a death-bed confession to his wife about the theft. She sent the heart to the Archbishop of Paris.

Over the next several years many people came forward claiming to be Louis Charles but none were ever proven to be so. Still the argument raged. Did Louis Charles actually die in prison or had he managed to escape? This controversy was finally put to rest in 2000 when DNA testing was done using material from the heart, hair samples from Marie Antoinette, her sisters Maria Johanna Gabriela and Maria Josepha, their mother Maria Theresa, and DNA from two living descendants of Maria Theresa, Queen Anne of Romania and her brother, Prince André de Bourbon Parme. The DNA test performed was that of mitochondrial DNA and the results proved that the mummified heart did indeed belong to Charles Louis.

Mitochondrial DNA (mtDNA) is DNA found within the cells of the body. It is not located in the nucleus of the cell as is the standard DNA used for DNA profiling, but rather is found out in the cytoplasm, the soup of the cell. mtDNA is passed down from generation to generation through the maternal line. The reason for this is quite simple. At the time of fertilization, the father only donates strands of DNA from the sperm, while the mother donates not only DNA but the first cell of the new offspring. So nuclear DNA will come from both mother and father while the mtDNA only comes from the mother.

As these cells divide and divide and divide to form the new individual, the mtDNA within the cells is also reproduced with each cell division. So the new offspring will have nuclear (genetic) DNA from both parents but mitochondrial DNA only from the mother. This is true of both male and female children. The difference is that only female children can pass this mtDNA along to the next generation.

Several other factors make mitochondrial DNA very useful in determining maternal ancestry. It is very hardy and tends to remain intact over a longer time and under many conditions that would destroy or make unusable nuclear DNA. Also, it can be obtained from tissues that do not contain nuclei within the cells. Things such as hair. Nuclear DNA is only found in the bulb or follicle of the hair where complete cells reside, while mitochondrial DNA is found within the shaft. This is simply because as hair grows it is composed of dead cells from the follicle. As the cells die, their nuclei are stripped away, and they are added to the growing hair. So the hair shaft will contain mtDNA but not nuclear DNA. The last important thing about mtDNA is that it mutates very rarely, perhaps only every 4-5000 years. This means that your mitochondrial DNA matches that of your mother, your maternal grandmother, your maternal great-grandmother, and on back up the maternal line for many generations.

This sturdiness and longevity of mtDNA is what allowed tissues obtained from young Louis Charles’ mummified heart to be compared with the hair from his mother, his maternal aunts, and his maternal grandmother. The match proved the the future Louis XVII came from this maternal line.

Louis Charles Heart

Louis’ heart now rests within a silver urn at the Baslique Saint-Denis near Paris, where the remains of all but three French Kings are buried, including Louis Charles’ parents, King Louis XVI and Marie Antoinette.

Wikipedia Article

Archaeology Article

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