Rapid Blood Test to Predict Covid-19 Disease Severity

• 18 Jan 2021

Why in News

Scientists at Washington University School of Medicine in St Louis (WUSTL) have published a paper showing that a relatively simple and rapid blood test can predict which Covid-19 patients are at highest risk of severe complications or death.

Key Points

• About the Blood Test:
  
  • It measures levels of mitochondrial DNA, a unique type of DNA molecule that normally resides inside the energy factories of cells.
  • Mitochondrial DNA spilling out of cells and into the bloodstream is a sign that a particular type of violent cell death is taking place in the body.
• Study Conducted:
  
  • The team evaluated 97 patients with Covid-19, measuring their mitochondrial DNA levels on the first day of their hospital stay.
  • They found that mitochondrial DNA levels were much higher in patients who eventually were admitted to the ICU, incubated or died.
    
    • This association was independent of a patient's age, sex and underlying health conditions.
• Significance:
  
  • The test could serve as a way to predict disease severity as well as a tool to better design clinical trials, identifying patients who might, for example, benefit from specific investigational treatments.
  • The test could serve as a way to monitor the effectiveness of new therapies. Presumably, effective treatments would lower mitochondrial DNA levels.
  • Further, the test predicted outcomes as well as or better than existing markers of inflammation currently measured in Covid patients.
    
    • Most other markers of inflammation measured in patients with Covid-19, including those still under investigation, are general markers of systemic inflammation, rather than inflammation specific to cell death.
    • Inflammation is the body’s innate response to injury or infection (including trauma, surgery, burns, and cancer).
      
      • Certain proteins are released into the bloodstream during inflammation; if their concentrations increase or decrease by at least 25%, they can be used as systemic inflammatory markers.

Mitochondrial DNA

• It is the small circular chromosome found inside mitochondria.
  
  • The mitochondria are organelles found in cells that are the sites of energy production. They produce cellular energy in the form of adenosine triphosphate (ATP), hence they are called ‘power houses’ of the cell. The mitochondria divide by fission.
• It is different in a way from the DNA (Deoxyribonucleic Acid) that's in the nucleus.
  
  • Mitochondrial DNA is small and circular. It has only 16,500 or so base pairs in it. It encodes different proteins that are specific for the mitochondrial.
  • The nuclear genome is linear and is made of 3.3 billion DNA base pairs.
  • The mitochondrial genome is not enveloped, and it is not packaged into chromatin.
  • Mitochondrial DNA, unlike nuclear DNA, is inherited from the mother, while nuclear DNA is inherited from both parents.
• If there's a defect in some of those mitochondrial DNA bases, that is to say a mutation, one will have a mitochondrial disease, which will involve the inability to produce sufficient energy in things like the muscle and the brain, and the kidney.

Source: IE