Written by Macrogen Corp.
Various types of home diagnostic testing or screening have placed more power and control of individual health information and care in the hands of consumers. We are well familiar with and may have used (or know someone who has) blood pressure kits, glucose measurement kits, and home pregnancy tests. Due to the next-generation sequencing (NGS) revolution, it is now possible to achieve home DNA sequencing for medical applications. However, clinical DNA sequencing remains the best approach for genomics-based diagnosis given the healthcare technical expertise available, the variety of tissue samples that can be used for testing, the range of sequencing approaches (such as whole genome sequencing ([WGS]), the reliability of results, and the appropriate interpretation by medically-trained professionals.
Home DNA Sequencing
Home DNA Sequencing services (or direct-to-consumer DNA testing) are now available by a number of companies. Most companies (such as Pathway Genomics) use a small sample of saliva to extract DNA for sequencing. Unlike the other familiar home tests, the consumer does not perform the sequencing. The saliva sample is sent to the company which then performs the sequencing and analysis. Those using the home DNA sequencing services receive information about disease risk once the DNA is analyzed. This process typically has a 4-week or more turnaround time.
A possible future variation in home DNA sequencing can involve devices that perform sequences at home and that do not require the shipment of samples for analysis. A device using nanopore sequencing technology (MinION), may represent a sign that home DNA sequencing may be going in that direction. The small portable device, which is currently only used by research institutions, performs the sequencing and connects to a computer via USB cable. The data is analyzed by a related program available in the cloud.
Clinic DNA Sequencing
In the clinical setting, the goal of patient DNA sequencing is not only to identify risk of disease development, but to help diagnose a variety of disease with a genomic basis. Although NGS is not yet used routinely in the clinic, this is the direction in which personalized medicine is rapidly moving. Commercial genome facilities currently assist healthcare providers in obtaining genetic sequencing data and their interpretation so that the provider can apply this to healthcare delivery. This approach is considerably more reliable than the home test route for a number of reasons. Healthcare personnel are much better trained in obtaining appropriate samples to submit to laboratories performing NGS services. The commercial laboratories use validated procedures and reliable databases to identify matches and trends.
Clinic-related DNA testing is not limited to SNP sequencing as is common with home testing. Whole genome sequencing can be used for diagnostic oncology panels, noninvasive prenatal testing, diagnosis of rare genetic disorders, infectious agent detection, determining personalized treatment strategies, and more. Another benefit of clinical DNA testing is the interpretation by medically-trained personnel who can more accurately apply the information to the individual’s specific medical issue or concern. This is very important since potentially alarming information can adversely affect a patient, while other information may be overlooked and lead to health effects that could be prevented.
Technical Differences between Home and Clinical DNA Sequencing
The primary technical differences between home and clinic DNA sequencing are:
1) Home testing uses saliva samples (and blood samples when a healthcare provider is involved), while blood and other samples that may be more appropriate can be used in the clinical setting.
2) Home testing is typically limited to the sequencing of SNPs, while WGS can be used in the clinical setting.
3) Home testing provides information on disease risk based on a database of biomarkers; clinic testing can involve the detection of infection disease, help in strategizing treatment approaches, assist in noninvasive prenatal testing, and more.
4) Validation and accuracy of home testing services are inconsistent, while testing by full-service clinical sequencing facilities are based on validated procedures.
The most important nontechnical difference between home and clinic DNA sequencing is the benefit provided by the latter of the interaction with a clinician who can give guidance in the interpretation of the results. There are also concerns with data privacy with home testing service providers. Home tests may not be covered by insurance, while performing the services by companies interacting with a healthcare professional may be covered by health insurance.
Even with doctor interaction and genetic counseling, knowing more intimately the risk of disease development can increase concerns regarding future health status and whether or not preventative actions may need to be taken. An example is the case of Angelina Jolie who opted for a double mastectomy upon learning of her BRCA1 mutation status. With home tests, there is no doctor interaction, although the results can be taken to a doctor for further interpretation and receipt of related counseling. Studies conducted by van der Wouden et al show that home test consumers eventually seek healthcare counseling at varying times after receiving results1.
Studies have been conducted to determine the likelihood of home test takers having increased health concerns once receiving knowledge of their genetic risk factors. Carere et al. found that those who had their DNA analyzed by home DNA sequencing companies had higher perceived risk of developing a disease upon receiving elevated risk results2. There are concerns by many healthcare professionals that consumers would have difficulties understanding the meaning of the home –testing results. Interestingly, a study by Ostergren et al. indicates that most consumers do understand the results, but this mainly corresponded to the educational and genetic knowledge levels of the consumers3.
Personal genetic testing provides individuals opportunities to take proactive and informed roles in their healthcare. However, the most beneficial aspect of this new information increases with the accuracy of the data and interpretations provided. Genetic or health counseling is very valuable in assisting patients to assimilate the information so that misjudgments do not lead to deciding adverse actions that may not be needed or to a lack of action leading to missed opportunities to prevent disease development.
- Ostergren JE, Gornick MC, Carere DA, et al. How Well Do Customers of Direct-to-Consumer Personal Genomic Testing Services Comprehend Genetic Test Results? Findings from the Impact of Personal Genomics Study. Public health genomics. 2015;18(4):216-224. doi:10.1159/000431250.
- Carere DA, Kraft P, Kaphingst KA, Roberts JS, Green RC. Consumers report lower confidence in their genetics knowledge following direct-to-consumer personal genomic testing. Genetics in medicine : official journal of the American College of Medical Genetics. 2016;18(1):65-72. doi:10.1038/gim.2015.34.
- van der Wouden CH, Carere DA, Maitland-van der Zee AH, Ruffin MT 4th, Roberts JS, Green RC; Impact of Personal Genomics Study Groupâ€ . Consumer Perceptions of Interactions With Primary Care Providers After Direct-to-Consumer Personal Genomic Testing. Ann Intern Med. 2016 Apr 19;164(8):513-22.