Textbooks teach that to find if the liver is off, we should palpate, auscultate, percuss, and maybe even biopsy the liver. Except in metastatic cancer, there should be no trace of liver tissue anywhere but around the ligamentum teres hepatis where it belongs. However, we are learning that there is more fluidity across the units within our body. The public has been captured by the idea that microbes in our body may slip through tight junctions of the gut and spill into the circulation. And fundamentally, we now know that traces of tissue, cell-free DNA (cfDNA)3 for example, flow throughout bodily fluid. The use of cfDNA screening to detect fetal aneuploidy in maternal circulation by innovators like Dr. Dennis Lo has already revolutionized the way prenatal screening is done (1, 2).
The field of liquid biopsies is still young, and a recent development in the laboratory of Dr. Jay Shendure at the University of Washington brings a new dimension to uncovering the tissue of origin of cfDNA (3). Clinical Chemistry spoke with Shendure about his latest work.
What Is the Innovation?
Every cell in the human body, with some exceptions, has the exact same package of DNA. How then is a hepatocyte so different in form and function from a neuron? One answer lies in epigenetics—the selective control of specific genes in the development of an organism. And to regulate genes that a tissue type may or may not need, its DNA is packaged and bound …