Analyzing ancient DNA, an international team of researchers has uncovered cases of chromosomal disorders, including what may be the first case of Edwards syndrome identified from prehistoric remains.

The team identified six cases of Down syndrome and one case of Edwards syndrome in human populations living 4,500 years ago in Spain, Bulgaria, Finland and Greece.

Research indicated that these individuals were buried with care, and often with special grave goods, indicating that they were valued as members of primitive societies.

The global collaborative study, led by first author Dr Adam “Ben” Rohrlach of the University of Adelaide and senior author Dr Kay Profer of the Max Planck Institute for Evolutionary Anthropology, screened DNA from nearly 10,000 ancient and pre-modern humans for evidence. I was involved. of autosomal trisomies, a condition where people carry an extra (third) copy of one of the first 22 chromosomes.

“Using a new statistical model, we screened DNA extracted from human remains from the Mesolithic, Neolithic, Bronze and Iron Ages to the mid-1800s. We identified six cases of Down syndrome,” said Dr. Statistician Dr. Rohrlach says. from the School of Mathematical Sciences at the University of Adelaide.

“While we expected that people with Down syndrome certainly existed in the past, this is the first time we have been able to reliably detect cases in ancient remains, because their reliability by looking at skeletal remains cannot be diagnosed with

Down syndrome occurs when an individual carries an extra copy of chromosome 21. The researchers were able to find six cases using a novel Bayesian approach to accurately and efficiently screen tens of thousands of ancient DNA samples.

“The statistical model indicates that when an individual has about 50 percent too much DNA that comes from a specific chromosome,” Dr. Patixuca de Miguel-Ibanez of the University of Alicante and lead of the Spanish sites Osteologists say.

“We then compared the remains of individuals with Down syndrome for common abnormalities such as bony irregularities, or cranial ridges, which could help identify future cases of Down syndrome when the ancient DNA could not be recovered.”

The study also revealed a case of Edwards syndrome, a rare condition caused by three copies of chromosome 18, which comes with more severe symptoms than Down syndrome. The remains indicate severe abnormalities in bone development and a gestational age of death of approximately 40 weeks.

All cases were traced to perinatal or infant burials, but from different cultures and time periods.

Dr. Rohrlach says, “These individuals were either buried according to the standard practices of their time or were given special treatment in some way. This indicates that they were members of their community. were recognized as and were not treated differently at the time of death,” says Dr. Rohrlach.

“Interestingly, we discovered a single case of Edwards syndrome, and there was a significant increase in Down syndrome cases among early Iron Age individuals in Spain. The remains cannot confirm that these children survived to birth. , but they were among infants. Buried inside houses in the settlement, or inside other important buildings,” says Professor Roberto Risch, co-author and archaeologist at the Autonomous University of Barcelona.

“We don’t know why this happened, because most people were cremated during that time, but it seems they were deliberately selecting these infants for special burials.”

The research has been published in the journal Nature Communications and was part of a large collaborative project involving University of Adelaide researchers including Dr Adam “Ben” Rohrlach, Dr Jonathan Toke and Associate Professor Bastian Lamas, as well as researchers from around the world including the Max Planck Institute for Evolution. Anthropology in Germany where the data were generated.