Everyone has two copies of each set of genes from both parents. If a person inherits a mutation in a Lynch syndrome gene, they still have the normal copy of the gene from the other parent. Cancer occurs when a second mutation affects the normal working copy of the gene, so that the person no longer has a copy of the gene that works properly. Unlike the inherited Lynch syndrome mutation, the second mutation would not be present throughout the person’s body, but would only be present in the cancer tissue. However, not everyone with Lynch syndrome will get cancer. You and your family members are more likely to have Lynch syndrome if your family has a strong history of colorectal cancer. Family members who inherit Lynch syndrome usually share the same mutation. If one of your family members has a known Lynch syndrome gene mutation, other family members who get genetic testing should be checked for that mutation. (source: CDC.gov)
GENETICS & GENOMICS: SIMILAR BUT DIFFERENT
Excerpted from https://robertaklinemd.com
Genetics and genomics sound alike and are often used interchangeably. While they both deal with changes in our DNA, there are important scientific and clinical distinctions.
GENETICS CAME FIRST
DNA contains the genetic code, the blueprint for everything that happens in our bodies. DNA is short for deoxyribonucleic acid, and it is composed of long strands made up of four different nucleotides called adenine, guanine, thymine, and cytosine, or A, G, T, and C for short. It exists as two long strands that are paired in a specific manner. The DNA is grouped into functional units called genes, which can comprise either a small or large section of DNA.
This DNA code is incredibly complex, and in order to contain all this information, the amount of DNA we each have in our cells is tremendous. In fact, every cell contains about 6 feet of DNA. That’s enough DNA in one person that, if stretched out, it would be long enough to go to the sun and back more than 300 times… or go around the earth’s equator 2.5 million times!
That’s where chromosomes come in. The DNA is compressed into tightly coiled structures called chromosomes in order to fit into our cells. We each have 23 pairs of chromosomes, and they are stored in a special compartment of the cell called the nucleus.
While that solves the storage problem, it creates a different problem – how to access the instructions encoded in the DNA. Every time that cell needs to replicate itself to replace dead cells in an organ or tissue, or we need to make a certain protein, portions of the chromosome need to be unwound to expose the needed genetic code. But sometimes during that process mistakes are made, and the change in the DNA can be mild or catastrophic.
GENETICS: BLACK & WHITE
With a traditional, single-gene disorder such as Tay-Sachs disease, genetic information is obtained from a patient as well as his or her immediate family members and relatives. The information is then used to diagnosis or predict the risk of an inherited genetic disorder passing from one generation to another. For many single-gene disorders, there are very limited medical interventions available. Genetic disorders are individually rare, and they account for about 5% of all human disease.
That meant 95% of the diseases were due to some other mechanism. In an effort to better understand how DNA contributes to health, scientists realized that genetic mutations were only part of the story. The Human Genome Project was conceived in the late 1980’s to provide answers.
One of the biggest take-aways from the Human Genome Project was that humans share 99.5% of their genome. But while this means we are far more alike with all the genes we have in common, that 0.5% difference is significant. The small differences are what make us each unique.
Genomic Medicine: It is now possible to use results from clinically-based genomic testing to evaluate a person’s disease susceptibility, and develop evidence-based, personalized intervention strategies to reduce those risks. These strategies include DNA-directed lifestyle modifications, dietary recommendations, nutritional supplements and/or exercise, all of which influence how these genes function to create health or disease. Biomarker testing can then be used to evaluate whether the intervention is efficacious. With this approach, the guess-work and inefficiencies of trial-and-error strategies are greatly reduced, leading to better health more quickly and cost-effectively.
A comprehensive test can provide gender-specific reports to create personalized programs for many health conditions, including:
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About the Author
Dr. Kline is a board-certified ObGyn physician, Integrative Personalized Medicine expert, consultant, author, and educator whose mission is to change how we approach health and deliver healthcare. She helped to create the Integrative & Functional Medicine program for a family practice residency, has consulted with Sodexo to implement the first personalized nutrition menu for healthcare facilities, and serves as Education Director for several organizations including the Women’s Diagnostic Health Network, Mommies on a Mission. Learn more at https://bobbiklinemd.com
LYNCH SYNDROME is a hereditary cancer condition in which a mismatched repair gene, which ordinarily repairs errors in DNA duplication, is defective. As a result, individuals are predisposed at a very high lifetime risk of cancer, including an up to 85% risk for colorectal cancer, 65% risk for uterine cancer, 19% risk for gastric cancer, 13% risk for ovarian cancer and a higher than average risk for other cancer including cancers of the liver, gallbladder, kidney, bladder, prostate, pancreas, skin, brain and breasts. With genetic testing, there is hope...once diagnosed, annual cancer screenings take place and cancers can be treated or removed before becoming life threatening. By knowing our family history and having a great medical team, we live longer than ever before...as long as anyone else!
1) Cancer Heredity / NIH: https://www.cancer.gov/about-cancer/causes-prevention/genetics