Oldest Case of Klinefelter Syndrome Discovered

Australian National University wrote that the oldest case of a rare genetic condition has been discovered in a 1,000-year-old skeleton from Portugal. Klinefelter syndrome gives men an extra X chromosome.

What is Klinefelter Syndrome? Mayo Clinic explains that it is a genetic condition that results when a boy is born with an extra copy of the X chromosome. Klinefelter syndrome is a genetic condition affecting males, and it often isn’t diagnosed until adulthood.

According to Mayo Clinic, Klinefelter syndrome may adversely affect testicular growth, resulting in smaller than normal testicles, which can lead to lower production of testosterone. The syndrome may also cause reduced muscle mass, reduced body and facial hair, and enlarged breast tissue. The effects of Klinefelter syndrome vary, and not everyone has the same signs and symptoms. Most men with Klinefelter syndrome produce little or no sperm, but assisted reproductive procedures may make it possible for some men with this condition to father children.

Mayo Clinic also stated that signs and symptoms of Klinefelter syndrome vary widely among males with the disorder. Many boys with Klinefelter syndrome show few or only mild signs. The condition may go undiagnosed until adulthood or it may never be diagnosed. For others, the condition has a noticeable effect on growth or appearance. Signs and symptoms of Klinefelter syndrome also vary by age.

Archaeology, a publication of the Archaeological Institute of America, reported that Klinefelter syndrome is not inherited, but is the result of a random genetic error after conception. People born with Klinefelter syndrome may experience low levels of testosterone, and the condition can also affect physical and intellectual development. 

Australian National University provided more details, including that Klinefelter syndrome is a rare genetic disease occurring in approximately one in 1,000 genetic-male births. 

The study was coordinated by Dr. João Teixeira, an ARC DECRA Fellow at the Australian National University (ANU), brought together by a multidisciplinary team that combined genetic, statistical, archaeological and anthropological information to establish a definitive diagnosis. 

The team began by analyzing genetic information obtained from a skeleton found in northeastern Portugal that had been radiocarbon dated to the 11th century by researchers from the University of Coimbra in Portugal. The researchers say the findings will help establish a historic record for Klinefelter syndrome, as well as enhance understanding of its prevalence throughout human history.

Associate Professor bastion Llamas, Head of Molecular Anthropology at the Australian Centre for Ancient DNA, said: “In recent years, ancient DNA helped rewrite the history of worldwide human populations. Our study demonstrates it is now a valuable resource for biomedical research and the growing field of evolutionary medicine.”

The DNA was extracted by a PhD student at the University of Adelaide, Xavier Roca-Rada, who said, “genetic analysis was undertaken to computationally map the degraded DNA fragments of the X and Y chromosomes to the reference human genome.”

Given the well preserved state of the specimen, the researchers were also able to determine physical traits in the skeleton compatible with Kleinfelter syndrome. Dr. Teixeira said, “While the study offers compelling evidence for the genetic history of Klinefelter syndrome, no sociological implications can be drawn from this diagnosis.”

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