Author: Shonee Lesh, MS, CGC.

I have been a genetic counselor for nearly 20 years. I have done everything from prenatal to adult genetics.  No matter which discipline I was working in, family history has always been my number one tool.  Your personal and family history can hold clues to the types of health risks you may be at risk for.  Therefore, it is important to ask the questions and document the health conditions that run in your family.  It is important to know that sometimes the clues are not obvious or are hidden from view. In general, family history is a very powerful tool.

For some time now, the world of genetics has discussed the possibility of sequencing a person’s whole genome in order to use this information to better prepare for potential health conditions and perhaps even prevent them.  Thanks to Francis Collins, Craig Ventor and many others, we have now sequenced the human genome. However, we have barely scratched the surface as far as understanding what it all means.  With the evolution of sequencing technology and bioinformatics, genetic testing as a tool is becoming even more relevant to society.

As a Professional Genetic Counselor, I needed to begin learning how to counsel people through sequencing their whole genome and decided to experience it first hand by sequencing my own genome.  Before that occurred, I took a full family history on myself.  I discovered approximately five hereditary conditions that were present in my family; hemiplegic migraines, hearing loss, celiac disease, hypertrophic cardiomyopathy, and hereditary hemochromatosis.  I was, therefore, expecting some of these to potentially show up on my genetic test.

As I sat down with my doctor to review my genetic test results, we found the answer to one of the five hereditary conditions running in my family.  I was found to be a carrier of hereditary hemochromatosis.  This is a recessive condition, which means if you have two faulty genes for hemochromatosis you may eventually develop high iron levels.  I had only one faulty copy, which is unlikely to ever affect my health.  We also discovered to our surprise an incidental finding. I am a carrier of MUTYH, a recessive condition resulting in an increased risk to develop colon polyps and colon cancer.  I am only a carrier of one faulty copy of this gene.  However, people with this condition may have a slightly higher than average risk for colon cancer than those who carry just one faulty copy. According to the guidelines, I should start colonoscopy at age 40 and repeat every year, simple enough.  Because these genetic traits are inherited I have warned my family members so that they can have the opportunity to be tested in order to be watchful and to prevent disease.

What does this mean for the other four hereditary conditions in my family?  Am I off the hook for these?  Sadly, the answer is “no”.  I must still be watchful for these other issues that run in my family.

Why is that you may be asking yourself?  The reason is that we do not fully understand the human genome even though we may know its alphabet.  It’s possible that I did not inherit some of these conditions that run in my family and that would be great to hear.  However, to truly rule out these conditions in myself, some of my affected family members would need to be tested first to make sure the genetic cause can be identified by this test.  Until that happens, I will need to continue to be watchful for signs of these conditions and do what I can to prevent disease when possible.

As my example shows, both family history and genetic testing matters.  Each are powerful tools on their own, but when used in combination, it’s like having a superpower!