Genetic or DNA testing is used to explore a person’s risk of disease and/or whether the disease can be passed to future generations. Nowadays, there are over 1,000 genetic tests proficient in diagnosing many different genetic disorders with the most common being cancer and heart disease.
Heart disease is the leading cause of death in the US. Familial hypercholesterolemia (FH) is an inherited disorder that affects 1 in 250 leading to early cardiovascular disease. When cancer and heart disease arise due to a genetic cause, it’s usually a complex multi gene and environmental involvement vs. a single gene as is in over 6000 human diseases.
When it comes to cancer, most people are familiar with mutations in the BRCA gene; however, there are over 50 hereditary cancer syndromes caused by mutations in other genes as well. All in all, about 5 to 10 percent of cancer can be contributed to inherited mutated genes.
Due to the complexity involved, there isn’t a solitary genetic test that can be done to detect all genetic disorders, unfortunately. Molecular genetic tests that analyze a single gene are used to verify whether or not an individual has a mutated version of a known gene notorious for causing a particular genetic disorder which is the case for sickle cell anemia.
Single gene disorders are classified into three categories based on the way genes get passed from one generation to the next which consist of the following:
Recessive, dominant or X-linked.
According to the World Health Organization (WHO), the global prevalence of all monogenic diseases is approximately 10 in 1,000. Panel testing (testing many genes at once) is another type of genetic test that can be done; typically the genes being tested in a panel are all known to play a role in a particular disease such as a breast cancer panel. Furthermore, genetic disorders such as Down Syndrome require whole chromosome testing since large segments could be missing, duplicated or otherwise altered. Down Syndrome has a prevalence of approximately 1 in 1,000 live births worldwide.
Genetic testing is taking place more than ever before. At this time, genetic testing is voluntary and not routine. Primary care physicians and/or genetic counselors order certain types of genetic tests based on the needs (and family history) of the individual. A recent Forbes article suggests regular genetic testing would result in finding genetic abnormality in 1% of the American population which is beneficial since many disorders can be treated if found early. Although 1% doesn’t seem like much, finding disease before it happens is better for the individual in addition to the health care burden on society as a whole.
Genetic counselors provide additional support once a primary care physician suspects a need for genetic testing. There are several concerns that alert primary care physicians including family history of a genetic condition or history of cancer. Not only do these counselors determine a genetic link to disease using genetic testing, they educate and aid in the process of possibly finding genetic linkage to disease. Specifically, they are capable of assisting in the following areas:
- Explain probability of a genetic condition occurring
- Discuss how genetic conditions are passed down in the family
- Discuss known causes of birth defects
- Recommend and order tests that can help diagnose a condition, and explain test results
- Discuss treatment options for a genetic condition
- Counsel people in dealing with feelings regarding genetic conditions
- Explore reproductive options
Interpreting genetic testing results can be challenging. Genetic counselors provide guidance in order to make it less confusing. Getting a positive result indicates that a genetic component was found, but it doesn’t always guarantee that a person will suffer from disease. Some positive results are predictive. Predicting risk allows for early treatment and/or changes in lifestyle that could decrease the likelihood of disease. On the other hand, a negative result (not finding a mutation) doesn’t assure a disease free life. Genetic tests are not perfect and some are better than others. Further testing may need to occur. Moreover, an inconclusive result is another possibility that doesn’t rule out genetic disorders or confirm a genetic mutation. Although we face these challenges among others, we have come a long way in genetic testing and continue to improve.