Intro to Genomics

By Dr. Steven M Johnson D.O.

Genetics, More Than Meets the Eye

Genomic and Nutrigenomic Testing is now here at Evergreen Medical Centre

Genetics is on the tip of everyone’s tongue as of late.  Our ability to explore the methylation cycles that keep our cells healthy, to peak into the nuances of how our individual mood, personality, aging, detoxification pathways, immune pathways, inflammatory pathways, hormonal pathways are programmed on the genetic level is now possible.  From this understanding we can become empowered to choose i foods, substances and health strategies which are better suited for our individual constitution and support the physiological pathways which will improve our neurological, psychological, hormonal, vascular and immune health.  Some of the genetic pathways even help explain what type of exercise will be better for us and even help us understand how we tend to think and feel in certain situations and why certain diets would be better or worse for us and influence our weight.  This new era of testing f used correctly can help us to be mindful and more self-determined as regards our health.  The new field of nutrigenomic testing will also help us to understand which foods are best suited for our unique digestive metabolism and how they play into allergic processes, detoxification and satiety.We each have a genetic legacy which we can now choose to work with supporting our weaknesses and understanding our strengths.

The Incredible Human Manual

Your genome, the sum total of your genetic legacy, may be viewed as a manual for the myriad of cellular functions that ultimately define you as a person.  With rare exceptions, every one of your cells contains an identical copy of this manual, with each cell utilizing the appropriate sections to fulfill a specific role within your body.

This incredible human genome manual comprises 23 volumes in duplicate

Upon first consideration, you might ask, 'Why the apparent redundancy? Why do we, or should we, have two copies of each volume?'  The duplicity of the human genome stems from the fact that you have inherited one copy of each of the 23 volumes from dad, and another from mom, ensuring the preservation and passage of their individual genetic legacies through you.

The volumes of this manual are known as your chromosomes, and the pages, your DNA. The encoded instructions within your DNA are your genes.  The letters on the pages of your DNA (the letters of your genes) are known as nucleotides.  Your genes are the discrete instructions from your genome manual that direct your cells to produce the plethora of proteins consistent with the role of each of your cells.

Examples of the proteins encoded within your genes include: enzymes, produced by several cell types, including those found in your digestive tract and liver; hormones, produced by cells from your endocrine organs; neurotransmitters, produced by your nerve cells; receptors, produced and displayed on the surface of almost all cells in your body and which play a crucial role in how your cells communicate with one another; immunoglobulins and cytokines, produced by cells of your immune system.

The dynamics of the production of these cell-type specific proteins: how much of each protein is produced, when they are produced, what versions are produced and how efficiently they perform their tasks, collectively contribute to your uniqueness as an individual.  Understanding the genetic underpinnings of the latter factors can provide valuable insights into the functional state of your body and can often highlight areas of potential inefficiencies well before they manifest as health concerns.

Single Nucleotide Polymorphisms

The inherent duplicity of your genome manual means that each cell of your body has the option of taking its directives from two gene pools: your maternal or paternal genetic legacies.

The maternal and paternal versions of any given gene you have inherited are known as alleles.

For some cellular functions, one or the other allele (gene version) is used, and yet for others, your cells may take directives from both.  Depending on the ancestry of your parents, the alleles of any given gene you have inherited may be identical, or may differ in their DNA sequence at one or more places. That is to say, there may be single nucleotide variations between the DNA sequences of your maternal and paternal alleles (for any given gene). In genetic terminology these variations are known as polymorphisms.  Therefore, these single nucleotide or single letter variations present between your alleles are known as single nucleotide polymorphisms (SNPs).

Your genome contains tens of thousands of examples of SNPs, representing the differences between the alleles of the ~ 30,000 genes you have inherited from your parents.

Single nucleotide polymorphisms in genes can result in functional differences between the versions of the protein encoded by either allele of a given gene. Your genome abounds with examples of SNPs that will affect several of your cellular functions to varying degrees.  Many of these functional variations will be so discrete they can be considered benign with little health consequences.  However, others, particularly when taken in aggregate or coupled with lifestyle deficiencies, can have important implications to your health.

Your personal catalogue of SNPs is your very own genomic fingerprint and contributes to your uniqueness as an individual.

Copy Number Variations (CNVs)

 Thousands of peer-reviewed studies have since confirmed that the genome of every human being contains multiple examples of this deviation from the norm. This phenomenon is known as genome copy number variations or CNVs.

Your genome will likely have a dozen or more CNVs throughout your 23 chromosome pairs, which will further contribute to your uniqueness as an individual.

The effect of CNVs on cellular function should be quite obvious.  Deviations to the 2-copy norm of your genome manual can often result in aberrant production, either too little or too much, of the proteins encoded by genes within the CNV.  Depending on the role these proteins play, there can be important implications to your cellular functions and ultimately to your health.

By understanding your unique genomic make-up, your healthcare practitioner is better able to appreciate the individuality with which your body functions and is better equipped to provide you with a more personalized preventative healthcare plan.  The accuracy of genetic testing is not 100%. Results of genetic tests must be taken in the context of clinical representation and familial risk as independently determined by a well-trained physician or authorized healthcare practitioner.