Researchers from the Australian National University have established what is believed to be the earliest confirmation of Klinefelter syndrome through DNA recovered from a millennial skeleton, with the findings reported in Lancet. This landmark discovery adds a long-sought data point to the understanding of how this chromosome-related condition has appeared across human history.
Klinefelter syndrome, first described in 1942, arises when a male carries an extra X chromosome. The condition influences physical development and cognitive trajectories, typically leading to smaller testicular size, taller stature, elongated limbs, and sometimes breast tissue enlargement. Its occurrence is estimated at about one in every 500 newborn boys, making it one of the more common chromosomal variation disorders observed in clinical genetics. In modern clinical practice, awareness of Klinefelter’s syndrome helps guide early diagnostic workups and tailored interventions that can support growth, puberty, and learning supports across the lifespan (attribution: Lancet).
In Portugal, an age-old burial—an oval tomb within the Torre Velha necropolis—revealed the remains of a man buried roughly a thousand years ago. The site, uncovered during ongoing excavations, featured a cemetery with numerous tombs but did not include accompanying grave goods or coffins with this particular body. The skeleton lay supine with feet oriented eastward, a Christian burial arrangement that aligns with established ritual norms of the period, and the deceased’s arms were crossed over the chest, a posture sometimes interpreted as a sign of respect or piety in burials of the era. These taphonomic details help researchers reconstruct ancient funerary practices and connect them to broader cultural and religious landscapes of medieval Iberia (attribution: Torre Velha excavations).
The investigative team approached the specimen with careful genetic analysis despite the challenge of highly degraded ancient DNA. By comparing the ancient genetic material with reference genomes, scientists were able to identify chromosomal patterns consistent with an extra X chromosome in the buried individual. The team corroborated this finding through careful examination of skeletal markers, including distinctive dental features and stature. The individual measured around 180 centimeters in height and exhibited dental and periodontal indicators, such as signs of chronic gum infection, that align with the broader phenotype associated with Klinefelter syndrome in modern clinical descriptions. This convergence of genetic data and hardy skeletal evidence strengthens the interpretation that the ancient individual carried an extra X chromosome (attribution: Lancet; methodological notes from the study).