Tuesday, November 22, 2022

Yersinia Pestis and ERAP2


The Black Death was the major cause of death in recorded history. Recent research suggests the Black Death has "...placed a significant selective pressure on the human population, changing the frequency of certain immune-related genetic variants and affecting (people) susceptibility to diseases today" The Black Death was caused by the bacteria Yersinia pestis. The disease killed between thirty to sixty percent of Europeans, North Africans and Asians. Dr. Luis Barreiro, Ph.D., Professor of Genetic Medicine at the University of Chicago, and participants in his study, examined ancient DNA samples from bones of over two hundred individuals from London and Denmark, who died before, during and after the plague. By using targeted sequencing for a set of 300 immune-related genes, the scientists discovered four genes that (while depending on variant) either protected against or increased susceptibility to Yersinia pestis. The team concentrated on one gene with a particularly strong association to susceptibility: ERAP2. Furthermore, individuals, who had two copies of one specific genetic variant, dubbed rs2549794, were able to produce full length copies of ERAP2 transcript (Barreiro 2022) Thus, producing more of the functional protein, compared to a different variant that led to a shortened and non-functional ERAP2 transcript. In addition, the research team tested how the rs2549794 variant affected the the ability of living human cells to help fight the plague, concluding microphages that express two copies of the variant were more effective when neutralizing the bacteria Yersinia pestis. It is fascinating to read and understand the significance of the experiment. Having access to ancient DNA and sequencing technologies to observe the unique characteristics of the organisms is captivating. To me, Genetic Medicine is compelling. It is the meeting point of science and human history. Who are we? Where do we come from? Why do we act the way we do? How much of this information can I deduce from my DNA? Those are questions that the methodology, philosophy and history of genetics and medicine urge me to seek answers. 

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