Wednesday, 4 April 2012

Ötzi The Brown Eyed Ice Mummy


            The ice mummy, affectionately called “Ötzi”, was discovered in the Tisenjoch Pass of the Ötztal Alpss in 1991 (shown on the map as a star near #1).  Immediately following his discovery and extraction, he was taken to the Archaeological Museum in Bolzano, Italy where studies of the well-preserved mummy began 3 years later.  Since that time, many interesting discoveries have been made in relation to Ötzi’s phenotype, including his blood type, eye colour and some insight into diseases he may have suffered from.


In 2010, scientists took a DNA sample from Ötzi’s ilium and began studies on his genotype. Geneticists were particularly interested in Ötzi’s genetic ancestry and were curious if his DNA was even close to any nearby modern people groups.  His DNA was compared to that of 1300 European samples, 125 North African samples (from Egypt to Morocco) and 20 Qatari samples.  Immediately, it was apparent that Ötzi’s DNA was much closer to that of Europeans and more specifically, South Western Europeans.  After further comparison with South Western European samples, geneticists were able to closely link Ötzi’s DNA with modern day samples from Northern Sardonia (indicated on the map with a 2) and Southern Corsica (3).


Ötzi’s phenotype was also of interest to scientists and findings indicate that a variation of the MCM6 gene implies that the ice mummy was probably lactose intolerant, although at this time, this would have been common.  This mummy dates back to the times when European agricultural practices were just beginning and therefore the ability to digest lactose was not yet an advantage, as it would become in the coming years.
Another interesting phenotype discovery was the calcification of some of Ötzi’s major arteries (carotid arteries – neck, off aortic arch - ,further from the heart, near belly button -  distal aorta and right iliac artery. – off from aorta, right leg).  One SNP (single nucleotide polymorphism), that is a genetic mutation in a single nucleotide of a strand of DNA, found in Ötzi’s genotype, has been repeatedly proven to increase ones chances by 40% of developing Coronary Heart Disease, as well as increasing the likelihood of strokes.  In addition to this gene mutation, three others were found that have also been linked to Coronary Heart Disease.


The conclusion was also reached that our friend Ötzi’s eye colour because several SNPs identified in his genotype are commonly associated with brown eyes.  Further proof came in the form of a study performed by Sturm et al.   This study had examined a collection of genes close together that happened to be present in Ötzi’s DNA.  In the study, subjects who shared this particular arrangement of genes had brown eyes 55.7% of the time.
Other interesting facts: Several indications were found that show that Ötzi belonged to the ‘O’ blood group and was Rh positive.  Scientists also found the bacteria called ‘B. Burgdorferi’. This is the earliest reported finding of these bacteria in humans, dating back about 5,000 years ago.

References
Coghlan, A 2012, Ötzi the ice mummy’s secrets found in DNA, New Scientist, viewed 15 March 2012, <http://www.newscientist.com/article/dn21523-otzi-the-ice-mummys-secrets-found-in-dna.html>.

Keller, A. et al. 2012. ‘New Insights into the Tyrolean Iceman’s origin and phenotype as inferred by whole-genome sequencing’, Nature Communications, vol. 3, no. 698, viewed 15 March, 2012, http://www.nature.com.ezproxy.library.uq.edu.au/ncomms/journal/v3/n2/full/ncomms1701.html.

Princeton University "About WordNet." WordNet. Princeton University. 2010. <http://wordnet.princeton.edu>


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