The Blood of Louis XVI

GuillotineThis post was chosen as an Editor's Selection for ResearchBlogging.orgA bloody handkerchief stored in an ornately decorated gourd seems like a gruesome keepsake, but that is exactly what scientists are using to obtain the presumptive genetic profile of King Louis XVI of France.

“Who would want such an odd souvenir?” you might ask. Well, apparently a bloody handkerchief was a perfectly acceptable memento from the French Revolution. It represented the power of the common person in the new republic of France.

Let me explain: In 1774, Louis XVI inherited the French throne and, with it, enormous responsibilities: The government was deeply in debt, and French citizens were impoverished and heavily taxed. Louis XVI and his financial ministers made a series of poor decisions, and by 1788, France was nearly bankrupt and Louis was very unpopular with his subjects. The king was pressured to convoke the Estates General, a legislative assembly that had not met since 1614, to discuss fiscal reform. This assembly only added to Louis’ problems, as the Third Estate, which was comprised of common people, declared itself the National Assembly and began plans to write a constitution and transfer more economic and political power to the general population.

The common folks grew more powerful, and in 1789, after several unpopular political decisions by the king, an angry mob forcibly moved the court from Versailles to Paris, where it was hoped the king would be more accountable to his subjects. In 1791, Louis tried to escape to northeastern France to rally support from royalists and allied nations and reestablish his authority. This escape attempt failed, and the royal family was returned to Paris and placed under heavy guard. Clearly, the king’s power was weakening.

Meanwhile, other monarchies within Europe became concerned about the events in France. In an attempt to restore the king to full power in 1792, the sovereign prince of the Holy Roman Empire led a successful military campaign against the new French government and issued the Brunswick Manifesto, which condemned to death any persons who opposed the king. However, many revolutionaries saw this manifest and the failed escape in 1791 as proof of conspiracy between Louis and foreign powers against France. In late 1792, the National Assembly abolished the monarchy, declared France a republic and accused Louis XVI of high treason. On January 15, 1793, he was convicted and sentenced to death. Louis was stripped of all power and beheaded on the Place de la Révolution. Eyewitness accounts of the execution describe how onlookers dipped handkerchiefs into the king’s blood afterwards as a memento.

Now, more than 200 hundred years later, scientists have analyzed DNA from one of those handkerchiefs and published their findings in Forensic Science International: Genetics (1). Blood samples were collected and sent for duplicate testing to laboratories in Bologna and Barcelona, where scientists extracted DNA and analyzed Y and autosomal STRs, mitochondrial DNA (mtDNA) and the HERC2 gene, which influences eye color.

Researchers generated a full Y-STR profile that belongs to the G2A haplotype and had no matches among 21,800 haplotypes in the Y Chromosome Haplotype Reference Database. A full autosomal STR profile was generated and did not match the profile of any laboratory members or the gourd’s owner, suggesting that the results were not due to contamination. mtDNA analysis revealed a rare N1b haplotype with several substitutions. Analysis of the rs12913832 single nucleotide polymorphism (SNP) of the HERC2 gene revealed the presence of a G residue, which is associated with blue eyes, and an A residue, which is associated with brown eyes. Such a G/A heterozygote is consistent with a blue-eyed person born of brown-eyed parents, such as Louis XVI.

To believe that these DNA profiles are those of Louis XVI, you also must believe that the handkerchief is authentic and contains his blood. Unfortunately, researchers were not able to prove that because there are no known genetic reference samples from Louis XVI with which to compare. However, at least one genetic means is still available to show that the blood belonged to Louis XVI. Louis and his wife Marie-Antoinette had several children, including a son Dauphin Louis XVII. The dauphin died in 1795, and his heart was preserved and is now stored at the Basilique Saint-Denis in Paris. In 2001 mtDNA was extracted from the heart, and analysis confirmed that the heart was that of Marie Antoinette’s son (2). While mtDNA analysis can’t tell us anything about the genetic relationship between Louis XVI and Louis XVII (mtDNA is inherited only through the maternal lineage), additional Y and autosomal STR analysis could.

Generating Y- and autosomal STR profiles from the heart and comparing these profiles to those generated from the handkerchief could confirm a father-son relationship. Y-STR profiles of a father and his sons should be identical because the Y chromosome is inherited unchanged, except for rare mutations, through the paternal lineage. Y-STR analysis has its limits though: Differences in the Y-STR haplotypes do not prove that someone else was the blood donor; there is always the possibility of nonpaternity.

For the autosomal STR results, scientists can perform statistical calculations to determine if the two profiles are consistent with a parent-child relationship. [Personally, I’d focus on the Y-STR analysis in this case because the statistical calculations required to show a familial relationship could be complicated by the high level of inbreeding within royal families at that point in history.] Nonetheless, these comparisons could provide strong evidence as to whether the blood on the handkerchief is truly that of Louis XVI.

Note: Since this article was posted, additional work has been done to try to confirm the source of the blood on the handkerchief. For more information, see Update: Is It the Blood of Louis XVI?.

1. Lalueza-Fox, C., Gigli, E., Bini, C., Calafell, F., Luiselli, D., Pelotti, S. and Pettener, D. (2010) Genetic analysis of the presumptive blood from Louis XVI, king of France. Forensic Science International: Genetics: doi:10.1016/j.fsigen.2010.09.007
2. Jahaes, E. et al. (2001) Mitochondrial DNA analysis of the putative heart of Louis XVII, son of Louis XVI and Marie-Antoinette. Eur. J. Hum. Genet. 9, 185–90.

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Terri Sundquist

Terri has worked as a Scientific Communications Specialist at Promega Corporation for more than 13 years, and prior to that, spent more than 5 years solving problems and answering questions as a Promega Technical Services Scientist. She graduated with B.S. degrees in Chemistry and Biology at the University of Wisconsin—River Falls, then earned her M.S. in Molecular Biology from the Mayo Graduate School in Rochester Minnesota.

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