Let's Try Genetic Testing

Last revised: January 26, 2025

This article explains in detail the mechanism and benefits of genetic testing kits available through mail order, as well as the relationship between lifestyle diseases and genetic risk, and introduces the potential of preventive medicine using genetic testing.

What Are Mail-Order "Genetic Testing Kits"?

Did you know that genetic testing has recently become easier to access than ever before? If you search for "genetic testing" on an online shopping site, you'll find genetic testing kits sold by a number of different companies. When you place an order, a testing kit is sent to your home; you collect a sample such as cheek cells or saliva and mail it back, and the results are provided at a later date.

Genetic testing used to be an advanced procedure available only at university hospitals or specialized research institutions. However, thanks to technological innovations such as next-generation sequencers (NGS) and DNA microarrays, testing costs have dropped dramatically [ref:1], and it is now possible for anyone to have their own DNA information examined for just a few thousand to a few tens of thousands of yen. This kind of consumer genetic testing (DTC: Direct-to-Consumer genetic testing) is rapidly expanding worldwide, and the number of users in Japan is also on the rise [ref:2].

How to Use a Genetic Testing Kit

Using a genetic testing kit is very simple. The process is designed so that even first-time users can complete the test without confusion, following the steps below.

1. Order the kit: Purchase a genetic testing kit through an online store or the official website.
2. Collect a sample: Using the dedicated swab or tube included with the kit, gently scrape the inside of your cheek or collect the specified amount of saliva.
3. Return the sample: Place the collected sample in the dedicated container and mail it to the testing laboratory using the included return envelope.
4. DNA analysis: The laboratory extracts the DNA and simultaneously analyzes hundreds of thousands to millions of genetic variants (SNPs).
5. Check the results: A results report arrives online or by mail a few weeks later.

In this way, the biggest advantage of mail-order genetic testing kits is that they let you obtain your DNA information easily at home, without needing to visit a medical institution.

What Genetic Testing Reveals — The Benefits of Knowing Your Disease Risk

So what are the benefits of taking a genetic test like this? The greatest benefit expected from learning about your own genetic information is the ability to understand your "disease risk" in advance.

For example, consider commonly known lifestyle diseases that many people worry about, such as diabetes, hypertension, and hyperlipidemia (dyslipidemia). These diseases actually develop from a combination of multiple causes, but they are called "lifestyle diseases" because daily habits such as diet, exercise, smoking, and drinking are major contributing factors.

However, by understanding your risk through genetic testing, you may be able to clarify what to improve in your diet, exercise, and daily rhythm, allowing for more efficient preventive action. Knowing which diseases you have a particular genetic predisposition toward can be considered the first step toward achieving what might be called "tailor-made health management."

Disease Risk Due to Genetic Differences — Why Outcomes Differ Even With the Same Lifestyle

Yet, as many of you know, even people who live the same lifestyle can be divided into those who develop diabetes, hypertension, or hyperlipidemia and those who do not. This may be because certain "genetic differences" cause disease risk to vary from person to person [ref:3].

Our bodies function through proteins encoded by roughly 20,000 to 25,000 genes. There are slight individual differences in the base sequences of these genes (genetic variants, or SNPs: single nucleotide polymorphisms), and these differences affect variations in constitution and susceptibility to disease.

The Difference Between Single-Gene Disorders and Multifactorial Diseases

There are various types of genetic disease. Disorders caused by a mutation in just a single gene are called "single-gene disorders (Mendelian diseases)," with well-known examples including cystic fibrosis, Huntington's disease, and sickle cell disease.

Lifestyle diseases, on the other hand, cannot be explained by a difference in a single gene alone; rather, differences in multiple genes are thought to interact with one another. These diseases are called "multifactorial diseases (polygenic diseases)," and they develop through a complex interplay of both genetic and environmental factors. For this reason, accurately assessing the risk of lifestyle diseases requires examining multiple genes at the same time.

Recent technological advances have been remarkable, making it possible to simultaneously analyze hundreds of thousands of SNPs or more in a single test. This allows for a comprehensive assessment of the risk of developing various diseases, including cancer, heart disease, and dementia.

Precautions When Using a Genetic Testing Kit

While genetic testing offers many benefits, there are also several precautions worth understanding before use.

• Risk figures are probabilities, not certainties: Even if a genetic test shows a "high risk of diabetes," it does not mean you will definitely develop diabetes. It is merely a statistical risk indicator.
• Results may differ between testing companies: Because each company analyzes different SNPs and uses different algorithms, results for the same person can differ slightly between providers.
• Prepare for the psychological impact: Learning about your genetic risk is valuable, but some people may feel anxious depending on the results. It's important to consult a genetic counselor or specialist about anything unclear.
• Managing personal information: DNA data is the ultimate form of personal information. Be sure to check the testing company's privacy policy and data management practices beforehand.
• Understand the difference from medical practice: DTC genetic testing is generally not a medical procedure and is not intended for diagnosis or treatment. If you receive a concerning result, be sure to consult a medical institution.

Clinical Use of Genetic Testing Is on the Rise

Beyond consumer genetic testing kits, the clinical use of genetic testing in medical settings has also increased dramatically over the past 20 years. According to a large-scale study using electronic health records, the number of clinical genetic test orders has increased roughly sixfold over the past two decades [ref:4], showing that the use of genetic information is becoming central to preventive medicine and personalized medicine (precision medicine).

In addition, genetic testing is also drawing attention for early detection and prevention of familial cancer risk [ref:5]. For diseases that are strongly influenced by genetic factors, undergoing genetic testing from a younger age can help set an appropriate frequency for screening tests and enable proactive lifestyle improvements.

Use Genetic Testing for Your Future Health Management

Genetic testing is a powerful tool for understanding the health risks you may face in the future. By reviewing habits such as diet, exercise, and sleep based on your test results, it may be possible to prevent or delay the onset of diseases for which you have a higher genetic risk.

Of course, genetic test results do not determine everything. Since lifestyle diseases develop through the interaction of genetic and environmental factors, the most important thing is to correctly understand your results and apply them to improving your daily habits.

Why not take this opportunity to undergo genetic testing and prepare for future disease risk? Scientifically understanding your own constitution is a major step toward a healthy, fulfilling life.

Frequently Asked Questions

Q1. How much does a mail-order genetic testing kit cost?

A. It varies depending on the testing company and the scope of the test items, but it generally costs a few thousand to a few tens of thousands of yen. The more test items included, the higher the cost tends to be, but costs have dropped significantly compared to the past thanks to technological advances.

Q2. Can genetic testing also reveal cancer risk?

A. Yes, many consumer genetic testing kits can examine the genetic risk of major cancers, such as breast, colorectal, and stomach cancer. However, these are strictly statistical risk assessments and differ from a definitive diagnosis made at a medical institution. If you are found to have a high risk, we recommend consulting a specialist.

Q3. If a genetic test shows a "high risk," will I definitely develop that disease?

A. No, not necessarily. What genetic testing shows is a statistical tendency toward "susceptibility," not a definitive diagnosis. It may be possible to reduce your risk through lifestyle improvements and regular health checkups.

Q4. Will collecting the sample myself still produce accurate results?

A. Yes, as long as you collect the sample correctly according to the instructions included with the kit, a sufficient quantity and quality of DNA can be obtained. DNA extraction techniques from oral mucosa or saliva are well established, and highly accurate analysis is possible even with at-home collection. That said, it's important to follow precautions such as avoiding eating, drinking, or smoking right before collection.

Q5. Should genetic test results be shared with family members?

A. Since genetic information is largely shared among blood relatives, if a risk for cancer or a hereditary disease is found, it is recommended that the information be shared with family members so you can consult a specialist or genetic counselor together. That said, whether to share it is ultimately up to the individual, so there is no obligation to disclose it if you'd rather not.

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