The Human Genome Project, an international collaborative research effort spanning ten years, identified the genetic building blocks of humans by cataloging the four DNA nucleotides (i.e., adenine (A), thymine (T), guanine (G), and cytosine (C)), a process known as genome sequencing. First published in 2001 and later updated in 2003, the Human Genome Project laid the groundwork for significant advancements in genomic technology. (20)(22) Although the human genome was deemed complete in 2003, researchers are still identifying new genes. In fact, a group of researchers released a preprint (not yet peer-reviewed) in May of 2021, claiming to have completed the human genome. (21)
The human genome is approximately 99.5% homogenous between individuals; however, some genetic sequence variations can occur in the remaining genome. These variations can be the result of polymorphisms or epigenetic modulation and may increase a person’s risk of developing certain conditions. (7)(23)
Using the power of genomic technology, practitioners now have the capability to take a more personalized approach to medicine. Are you wondering where genetic testing fits into an integrative medical practice? Read on to learn more about the benefits of genetic testing, the different types, and their clinical applications.
What is genetic testing?
Genetic testing analyzes cells and tissues to detect changes in genes, chromosomes, and proteins for diagnostic or risk assessment purposes. Practitioners may utilize genetic testing for various reasons, including:
- Assisting reproductive technologies such as in-vitro fertilization (IVF) through embryo testing
- Detecting genetic disease in fetuses
- Determining appropriate medications and dosages to meet individual needs
- Determining a person’s risk of developing a specific disease, particularly for conditions that run in families
- Determining whether an individual carries a gene for a particular heritable condition that can be passed onto offspring
- Diagnosing genetic conditions
- Screening newborn babies for life-threatening conditions, such as sickle cell disease (11)
Types of genetic testing
Genetic tests are not one-size-fits-all and are individualized based on a patient’s medical and family history. Types of genetic tests include single gene, panel, whole-exome sequencing, and genome sequencing.
Targeted single variant
Targeted single variant tests identify a specific variant in a single gene that is known to cause a disorder. Practitioners can use targeted single variant tests to test family members of individuals known to have a specific variant. (13)
Single gene testing
Single gene testing identifies changes in a single gene and is most commonly used by practitioners who suspect a patient has a certain condition or syndrome. Furthermore, single gene testing can be used when a patient’s family members have a known genetic mutation. (3)
Panel genetic tests are used to identify variants in multiple genes in a single test. Panel tests can help practitioners diagnose a patient exhibiting signs and symptoms that are characteristic of multiple conditions or when the suspected condition can be influenced by variants in multiple genes. (3)
Whole exome sequencing and genome sequencing
Whole exome sequencing and genome sequencing, also known as next-generation sequencing, analyzes a patient’s DNA for genetic variations and determines the order of nucleotides in their genetic code. (15) These tests may be used when single gene or panel tests are inconclusive or if the genetic cause of a condition is unknown. Due to the comprehensive nature of whole-exome sequencing and genome sequencing, these tests may be more time-effective and affordable than multiple single or panel tests. (13)
Clinical applications of genetic testing
Outlined below are the most common uses of genetic tests.
Carrier testing is a type of genetic testing used to identify individuals carrying a single copy of a gene mutation. Considering that it takes two copies of the same gene mutation–one from each parent–to cause a recessive disorder, carrier testing is most commonly recommended to couples trying to conceive, particularly those who have a family history of a genetic disorder such as cystic fibrosis, spinal muscular atrophy (SMA), sickle cell anemia, or Tay-Sachs disease. Other at-risk populations who may benefit from carrier testing before trying to conceive include individuals of African, African American, or Mediterranean heritage and those with Ashkenazi Jewish or French Canadian ancestry. (17)
Diagnostic testing is used to diagnose or rule out genetic or chromosomal conditions in patients exhibiting signs and symptoms. This type of genetic test has numerous applications and can be used to diagnose conditions at any point during the life cycle. At this time, diagnostic tests can identify gene alterations of some but not all conditions. Practitioners can use the results of diagnostic genetic tests to influence their patient’s treatment plans by suggesting lifestyle or dietary modifications or introducing medications or supplements. (14)
Direct-to-consumer (DTC) genetic tests provide limited information about a person’s medical and non-medical traits (e.g., predisposition for certain conditions, eye color). DTC tests are marketed to consumers and are widely available online and in many brick-and-mortar stores. Customers purchase an at-home testing kit, send in a sample of their saliva, and receive their results via the company’s website within several weeks. These tests do not require any practitioner authorization or oversight and are typically paid for out of pocket. (10) These tests can provide predictions about a person’s health and offer insights into their physical traits and ancestral background. (10) Depending on the company, DTC tests may have some limitations, including:
- Test results may not be accurate, or individuals may misinterpret results without practitioner guidance.
- They offer limited insights for certain health conditions or traits.
- Receiving unexpected information regarding health, family relationships, or ancestry may be stressful.
- There is limited oversight and regulation of companies offering these tests.
- Privacy may be compromised if testing companies don’t have adequate protection measures in place for patient records. (9)
Newborn screening is conducted on infants shortly after birth to identify inherited, life-threatening conditions affecting a child’s long-term health. The test, which requires only a few drops of blood from the baby’s heel, screens for genetic, endocrine, and metabolic disorders. (4)
Prenatal testing is offered to women during pregnancy to determine whether their baby is at risk of having a genetic or chromosomal disorder.
There are two types of prenatal genetic tests, including:
- Prenatal screening: Provides insights into the likelihood that the fetus has an aneuploid (missing or extra chromosomes), neural tube defects, and some other abnormalities
- Prenatal diagnostic testing: Uses cells from the fetus or placenta via amniocentesis or chorionic villis sampling (CVS) to determine whether the fetus has a certain disorder (14)
Predictive and presymptomatic testing
Predictive and presymptomatic genetic testing can benefit individuals concerned about their genetic predispositions to potentially inherited conditions. Predictive testing can identify genetic mutations that may increase an individual’s risk of developing a condition known to be influenced by genetic variations, such as breast cancer or hypertrophic cardiomyopathy. (14)(18) These tests can be performed at birth or any point during the life cycle. In contrast, presymptomatic testing is used to determine whether a patient will develop a genetic condition but has not yet exhibited signs and symptoms. (14)
Genetic test results: what do they mean?
Interpreting genetic test results can be challenging as they’re not always definitive and they can be influenced by numerous factors. Outlined below are the various test results and their potential interpretations:
- Positive: Positive results confirm a genetic change known to cause disease. A positive result of a predictive or presymptomatic genetic test does not determine the specific risk of developing a condition. (16)
- Negative: Negative results confirm that the test didn’t find a genetic change known to cause disease. A negative result indicates that an individual is not a carrier of a specific gene variant nor do they have an increased risk of developing a particular condition. (16)
- Uncertain: Uncertain results, also referred to as uninformative, indeterminate, inconclusive, or ambiguous, mean that the test can’t definitively confirm or rule out a diagnosis or determine an individual’s risk of developing a condition. Testing other family members can provide clarity in some instances. (3)
Benefits of genetic testing
Genetic testing can be an invaluable tool in your practice.
Allows you to personalize treatment plans
Knowing your patient’s genetic makeup can help you confidently prescribe an appropriate treatment plan. If a patient’s results suggest that they’re at risk of a specific chronic condition, you can recommend targeted supplementation to improve their overall health and well-being. (8)
Can influence lifestyle behavior changes
Genetic testing results can also help practitioners make recommendations for lifestyle modifications and dietary changes. A positive result can motivate some patients to make positive changes to their diet and lifestyle. A 2018 systematic review concluded that patients are more likely to make lifestyle behavior changes following genetic tests when provided with actionable recommendations. (6)
May offer peace of mind
If a patient has uncertainty about their health due to family history or signs and symptoms, genetic tests can provide some reassurance to patients if results conclude that they don’t carry a specific gene. (2) Regardless of the results, genetic tests can also offer clarity and provide a sense of relief to patients, allowing them to make informed decisions about their health. (12)
Downsides and limitations of genetic testing
Consider the following limitations of genetic testing.
Not always accurate
Although genetic testing has come a long way over the last two decades, it’s still far from perfect. Genetic tests have some limitations that may affect results, including suboptimal sensitivity and specificity. (8) The interpretation of genetic tests can also be challenging, considering that mutations can be influenced by various factors such as other genes, age, sex, and environment. (8)
Poses some psychological risks
If a genetic test confirms that a patient does carry a particular gene variant, this can trigger strong emotions of fear, anxiety, or guilt. Ease your patient’s concerns by reassuring them that possessing a gene variant does not guarantee that they’ll ever be diagnosed with a specific condition during their lifetime. (19) Genetic tests can also offer false reassurance in the event of false negatives or loss of hope in patients who receive positive test results. (8)
Although many patients may be motivated to make positive changes to their health after receiving their test results, some patients may be inclined to use positive test results to excuse or continue harmful behavior. For example, a patient with the ApoE4 allele, and consequently, a relative risk of 1.5 for developing coronary artery disease, may feel like they have no control over their health outcomes and may think that they’re destined to have a heart attack, regardless of their lifestyle. (8)
Counseling prior to genetic testing can help patients and their families mentally prepare for the results they may receive. (8)
Can be financially challenging
Genetic tests can cost upwards of hundreds to thousands of dollars, which may discourage or limit a patient from undergoing testing. Depending on the patient’s health insurance coverage, their plan may cover some or all of the costs involved. (19)
Find a genetic testing partner
One of the first steps to offering genetic testing in your practice is to choose a company that provides clinical genetic testing. Outlined below are some essential questions to consider when searching for a genetic testing partner:
- Do they provide results interpretation and implications of results?
- How do they secure confidential and sensitive genetic information? Do they have adequate facilities and servers for hosting patient records, and if records are stored in “the cloud,” does the company have firewalls and data encryption in place?
- How does the lab manage samples after testing?
- How long does it take to receive results?
- What are the qualifications of the clinicians who direct or supervise the lab? Does anyone on staff have a board certification in medical genetics?
- What is the lab’s clinical utility (e.g., the usefulness of a test in clinical practice)? (5)
Genetic testing with 3X4 Genetics
Ready to start implementing genetic testing in your practice? Fullscript’s integration partner 3X4 Genetics may be just the solution for you! 3X4 Genetics is an integrative healthcare company that uses the power of genetic testing to help practitioners create personalized treatment plans.
“3X4 Genetics is the missing piece I have been trying to find for my practice, and I cannot express enough how grateful I am that this company exists.” – Brooke Gacek, Clinical Dietitian, MS, RDN
3X4 Genetics offers a powerful turnkey solution with key features such as:
- On-demand access to industry-leading genetic tests based on 20+ years of scientific research and clinical practice
- Access to an online community of over 500 practitioners to network, collaborate, and brainstorm
- Genetics translation training to help practitioners translate test results to actionable insights
- Exclusive access to workshops and events led by industry thought leaders
- Genetic testing integration training to seamlessly introduce genetic testing to a practitioner’s practice
Did you know? All that’s required for a 3X4 Genetics test is a quick and pain-free 60-second rub with a cotton swab on the inside of the cheek. No blood is needed from the patient for the test.
The bottom line
There are many benefits of genetic testing for your clinical practice. It can help you provide more comprehensive and personalized preventative screening, clinical assessments, and care. Genetic testing may also encourage healthy behavior modifications and provide peace of mind to patients concerned about how their family history may influence their health. If you’re considering integrating genetic testing into your practice, search for a reputable genetic testing partner that can offer results interpretations, confidentiality, and more.
- American College of Medical Genetics and Genomics. (2021). ACMG technical standards for clinical genetics laboratories. Https://Www.Acmg.Net/ACMG/Medical-Genetics-Practice-Resources/Genetics_Lab_Standards/ACMG/Medical-Genetics-Practice-Resources/Genetics_Lab_Standards.Aspx?Hkey=0e473683-3910-420c-9efb-958707c59589
- Bowman‐Smart, H., Savulescu, J., Mand, C., Gyngell, C., Pertile, M. D., Lewis, S., & Delatycki, M. B. (2019). ‘Small cost to pay for peace of mind’: Women’s experiences with non‐invasive prenatal testing. Australian and New Zealand Journal of Obstetrics and Gynaecology, 59(5), 649–655.
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