The Complexity of Human Biochemistry

Today we take a digression into the science underpinning most medical advances today; a deepening understanding of human biochemistry.  A recent article on epigenetics in the New England Journal of Medicine reflects the ongoing struggle to get a grasp on healthy and diseased processes in the body.  (NEJM Article)   The sequencing of the human genome was at first thought to be the crowning achievement in the science of human biochemistry, but it turned out to be just another small stepping stone.  Our DNA may control some processes through various gene expression mechanisms, but DNA and gene expression are themselves subject to many feedback and external influences.  The sum of these influences is referred to as the epigenome.  DNA is a specific sequence of amino acid bases.  Certain units of that DNA are genes that produce downstream biochemicals.  Various other parts of DNA can influence when and how much expression of those biochemicals occurs.  Part of the epigenome is also the external environment, because it appears that this can also affect gene expression.  Some internal epigenetic factors are maintained during cell division, preserving their ongoing role in biochemistry.  Some forms of epigenetic information include methylation, post-translation modifications, and chromatin structure.  External influences on gene expression include diet, exercise and exposure to toxins.  The complexity of specific processes is astounding.  And all this complexity obviously provides multiple opportunities for things to go awry.  Cancer is often caused by epigenetic derailment.

All this complexity means that understanding disease or potential disease risks and processes in an individual can’t be done by a simplistic reading of their DNA, but must take into account a very wide range of factors and really would require periodic real-time testing of the various epigenetic influences to know their current state.  There is an enormous opportunity for creation of epigenetic diagnostic tools to provide advance warning about impending disease states.  A tall, but not impossible, task.  To me, it is a wondrous thing to understand the incredible complexity of human life, really any advanced life, and how that has evolved through thousands of generations.  When you read, for example, about certain RNA transcriptional processes, you have to be amazed at how such complex molecules with such complicated processes could arise.  But if you give evolution enough time and a large enough population, almost anything is possible. If you like learning, or just want to deepen your knowledge of the science that underlies medicine, articles like this one are well worth your time.