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The Molecular Stethoscope: RNA Levels in Blood Reveal Health Issues

Molecular-StethoscopeRibonucleic acid (RNA) is a single-strand biological molecule that performs essential roles within every cell of your body. Specifically, RNA plays an essential role in decoding, regulating and expressing genes. Together with DNA, RNA comprises a group of organic substances known as the “nucleic acids.” Nucleic acids, combined with protein, are essential to all known forms of life. RNA is essential because it acts as a messenger within the cell, switching genes on and off. Scientists use the letters G, A, U and C to represent RNA’s essential nucleotides guanine, uracil, cytosine and adenine.

A few RNA molecules act as catalysts within cells, either initiating essential processes or acting as relays for processes in progress. Doctors have been able to use DNA within the blood to detect cancer and the onset of several diseases for years. Now, for the first time, scientists are looking to enlist smaller, harder to detect RNA for that purpose. According to researchers at Stanford University, using RNA in this manner represents a major breakthrough in the quest to nip disease processes early.

The Molecular Stethoscope

By monitoring changing levels of RNA in the blood, scientists can generate a much more dynamic picture of what’s happening in the body than they can by using DNA alone. The difference is akin to comparing a still picture to a motion picture. Specific tissues are formed in the body by expressing specific genes, and specific RNA strands are required along the way. Therefore, when scientists detect rising RNA levels, they can determine the cause by identifying the specific RNA molecules.

This is similar to how clinicians identify issues with the heart by listening for specific sounds with a stethoscope, but on a much finer level. Stephan Quake of Standard University puts it this way, “We think of this technique as a kind of ‘molecular stethoscope, and it’s broadly useful for any tissue you care to analyze.”


Scientists can use this technology to look for issues during pregnancy, such as pre-eclampsia. Thanks to Quake’s work, doctors will be able to check a fetus for conditions like Down Syndrome. In fact, over 500,000 pregnant women have already had an early form of this test conducted. Doctors will also be able to track the health of the brain, heart, liver and kidneys over time by measuring RNA levels. Additionally, there is hope that this “molecular stethoscope” will allow doctors to determine the immune system’s response to an organ or hand transplant before symptoms appear. This would relieve the on-going stress that many transplant recipients feel.

“We’ve moved beyond just detecting gene sequences to really analyzing and understanding patterns of gene activity,” says Quake. He goes on, “Knowing the DNA sequence of a gene in the blood has been shown to be useful in a few specific cases.” As technology improves, Quake hopes that monitoring RNA will be the key to detecting virtually all disease processes before they get a hold on the body.

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