INVESTIGATING NATURAL SELECTION IN BEHÇET’S SYNDROME ACROSS SILK ROAD POPULATIONS

Behçet’s syndrome, a complex inflammatory disease with a significant genetic component, exhibits a high prevalence among populations historically associated with the Silk Road. This study investigates whether genes implicated in Behçet’s syndrome have been shaped by natural selection, potentially explaining their prevalence in those populations. Using data from the populations surrounding the Silk Road, originating from the Marco Polo Project of 2010 and the HGDP project, the datasets were merged and then pruned using Plink 1.9 to assess linkage disequilibrium. Subsequently, Principal Component Analysis was conducted to ensure the quality control of the merged dataset and to analyze the population structure. To investigate natural selection, the dataset was admixed and subjected to selection analysis using OHANA, a statistical methodology that employs maximum likelihood and Gaussian approximations to detect positive selection by analyzing allele frequency changes and population structure simultaneously. The results indicated that most genes associated with Behçet’s syndrome do not show signs of selection, suggesting that they evolved neutrally. However, a few chromosomal regions were potentially under positive selection. While not definitive, this suggests that certain genes may have been favoured historically. This dual influence emphasizes that both genetic drift and selection might have contributed to the genetic landscape of Behçet’s disease, offering new perspectives on its genetic origins and providing valuable insights into a condition that remains largely unknown and far from fully understood.