Oldest documented case of Down's syndrome discovered

Prehistoric - and most likely the oldest documented - cases of Down’s Syndrome, which is caused by having an extra copy of chromosome number 21, and an even rarer condition called Edward’s Syndrome, caused by carrying an extra copy of chromosome 18, have been announced this week by an international team of researchers. Writing in the journal Nature Communications, they’ve used highly sensitive DNA techniques to count the chromosome copy numbers in samples collected from ancient skeletons found in various places in Europe. The oldest goes back about 5000 years. The results show that not only were these same genetic conditions occurring at similar rates back in history, but ancient societies clearly cared for and cherished these individuals. Ben Rohrlach is at the University of Adelaide and one of the team who made the discovery, although they didn’t set out to answer this question specifically at the outset…

Ben - Initially we didn't have a question. We were just exploring what is a very, very large database of eight years now of sample collection at the institute I worked at. And I guess that once we realised that we could detect down syndrome and similar things, what we were really interested at that point was what we could tell about these individuals from their burials and from their skeletons that could inform us about more of their lives.

Chris - How does one go about detecting something like Down syndrome in ancient DNA?

Ben - What we did was we looked at the amount of DNA in a sample that came from each of the chromosomes. And in doing so, we could work out when we observed too much coming from one of them. And that was the indicator or the big red flag for Down syndrome and for Edwards syndrome.

Chris - What does this tell you about the likely frequency with which these conditions occurred historically compared to the modern era

Ben - With modern data, one of the only things we know that can affect the rate of cases of Down syndrome and Edwards syndrome is the age of the mother. And when we looked at how many cases we'd found, we found that it wasn't particularly different from the modern rate. But it's worth noting that because these individuals unfortunately had a short life expectancy before modern medicine, they were all quite young when they died, and it's difficult to find smaller and smaller skeletons. So we also don't know what we didn't find.

Chris - So what do you deduce then about how people back in the day, maybe even 5,000 years ago, regarded individuals with things like Down Syndrome and how they behave towards them?

Ben - I think from what we have observed, all we can say is that these cases, these six cases that we found, these babies were loved just as much as any baby today. One of these babies was buried with a very ornate necklace at another site. The baby was buried in the home and would've been with them long after the burial in sort of a spiritual way. And there was another case where the baby was buried in a beautiful dress in a Christian Church, in Helsinki. These babies were clearly cared for and loved. And I think that that's easy to understand because that's exactly how it would be today.

Chris - And in terms of the science behind this, how has this helped to push the envelope? What insights has this given scientists like yourself now looking at these sorts of questions?

Ben - I think the most critical thing is that it's possible and that people want to know about it. I think they're two really important points, but I think the third one from a purely scientific point of view is that we're starting to get enough ancient DNA samples and individuals in the record that we can start looking for things that weren't common. So we know a lot about the Black Plague because so many people are affected by it, but we don't know about these individual disorders, diseases, conditions. We don't know much about how the community viewed these people either, and we really don't know a lot about how they were cared for. And so I think this opens the door for those conversations, which were definitely there in archeology, but you can't diagnose these cases from just skeletons. You need the DNA. And so now it allows us to look at more cases, more conditions, and I think that pushes that envelope.

Chris - It's amazing to think we might be able to do a sort of molecular post-mortem 5,000 years after a person died and work out some of the diseases that they at least had, if not died from.

Ben - Absolutely. And the amazing part for me when I think about this is 5,000 years after the fact, we will discover these things and they will have never known. And it's sort of almost time travel in a sense.