GWAS（Genome-Wide Association Study）は、大規模なゲノムデータを解析し、脱毛リスクと関連のある遺伝的マーカーを特定する手法です。近年の研究では、脱毛リスクに関連する新たな遺伝子として、EDA2R遺伝子（毛包の発達に関与）やSOX21遺伝子（毛周期の調節に関与）が発見されています。
Genetic testing scientifically analyzes our hair quality and risk of hair loss, providing clues to predict the future condition of our hair. Hair thickness, curliness, and risk of hair loss are all closely related to genetic factors, and recent research has revealed their relationship. In this article, we will explain in detail the types of genes that determine hair quality and how to evaluate the risk of hair loss.
Genes that determine hair quality
Differences in thickness, curly hair, and straightness of hair are largely influenced by genes, and previous research has identified several key genes that play a role in hair quality.
1. EDAR gene
The EDAR gene is an important gene that determines hair thickness and density, and it has been found that certain mutations in this gene make Asian people more likely to have thick, straight hair.
2. TCHH gene
The TCHH (trichohyalin) gene is involved in the strength of hair curl. Variations in this gene affect the degree of curliness of hair, with a particularly pronounced effect in people of European descent.
3. WNT10A gene
This gene plays a key role in the development and maintenance of hair follicles, and mutations in it can affect hair growth and density, increasing the risk of hair thinning.
Genes and risk of hair loss
Hair loss, especially male pattern baldness (AGA) and female pattern baldness (FAGA), is known to be strongly influenced by genetics.
1. AR gene (androgen receptor gene)
The AR gene determines the function of the androgen receptor, which is affected by the male hormone (testosterone). If there is a mutation in this gene, the hair root becomes more susceptible to the hormone, making hair loss more likely to progress.
2. 5α-reductase-related gene (SRD5A2)
5α-reductase is an enzyme that converts testosterone into the more potent DHT (dihydrotestosterone). Certain mutations in the SRD5A2 gene lead to increased DHT production, shrinking hair follicles and making hair loss more likely.
3. FGF5 gene
The FGF5 gene controls the growth phase of the hair cycle. Mutations in the gene shorten the growth phase, making hair more likely to fall out before it has fully grown.
What genetic testing can tell you
Genetic testing can examine the following:
Hair thickness and quality (tendency to be straight or curly)
Risk of alopecia (possibility of AGA or FAGA)
Are you susceptible to the effects of hormones?
Length of the hair cycle and hair growth speed
By undergoing genetic testing, you can identify your risk of future hair loss and take appropriate hair care and preventative measures.
Latest research and evidence
Research into the relationship between genes and hair quality/hair loss risk is ongoing around the world. In particular, the following research is attracting attention:
“Relationship between the AR gene and AGA” (Reference link: Research paper link )
“Relationship between EDAR gene and hair thickness” (Reference link: Research paper link )
By utilizing genetic testing, we can gain a scientific understanding of hair quality and hair loss risk, allowing us to provide individually tailored care.
Benefits of genetic testing and how to use it
Genetic testing can provide important information about your hair type and risk of hair loss, which can be especially useful for those with a family history of hair loss or those who are concerned about the state of their own hair.
1. Early prevention and countermeasures are possible
If genetic testing reveals that you are at high risk for AGA or FAGA in the future, you can take appropriate measures early on. For example, you can take measures according to your individual risks, such as using hair growth products, reviewing your lifestyle, or receiving care from a specialist.
2. Distinguish between genetic and environmental factors
Hair loss is caused not only by genetic factors, but also by environmental factors such as stress and diet. By using a genetic test to find out to what extent your risk of hair loss is genetic, it becomes easier to determine whether lifestyle changes are effective.
3. Personalized care options
Choosing hair care products and treatments based on each individual’s genetic characteristics can lead to more effective approaches. For example, people who are sensitive to the effects of DHT may benefit most from using 5-alpha reductase inhibitors (such as finasteride).
Other genes that increase risk of hair loss
1. KRT81, KRT83, KRT86 (keratin genes)
Keratin is the main component of hair, and the KRT81, KRT83, and KRT86 genes are involved in hair strength and structure. Mutations in these genes have been shown to cause hair to thin and become more susceptible to breakage and damage.
2. SOD2 gene (oxidative stress resistance)
SOD2 (superoxide dismutase 2) is a gene that reduces oxidative stress in cells. Mutations in SOD2 can lead to accelerated aging of hair follicles and increased risk of hair loss.
3. MC1R gene (related to hair color)
The MC1R gene regulates melanin production, influencing hair color, and variations in this gene have been shown to increase the susceptibility to graying hair and may also play a role in hair health.
Lifestyle habits to prevent hair loss
Although genetic factors play a role, it is possible to reduce the risk of hair loss by taking measures such as environmental factors and lifestyle changes.
1. Balanced diet
A balanced diet is essential to maintain healthy hair. The following nutrients are especially important for hair growth:
Protein (makes keratin, the main component of hair)
Vitamin B complex (activation of hair matrix cells)
Iron (improves blood flow and delivers nutrients to hair roots)
Zinc (a mineral that helps prevent hair loss)
2. Stress management
Stress can cause poor circulation and hormonal imbalance, which can lead to hair loss. Yoga, meditation, and moderate exercise can help reduce stress.
3. Scalp massage and scalp care
Scalp massage is effective in promoting blood circulation and delivering nutrients to the hair roots. It is also important to choose an appropriate shampoo and improve the scalp environment.
4. Improve your sleep quality
During sleep, growth hormones are secreted and hair matrix cells become more active. Getting quality sleep can help promote healthy hair growth.
How to take a genetic test
Genetic testing is easily available at medical institutions and through online services.
1. Use a test kit
Many genetic tests can be done simply by taking a sample from your mouth. All you have to do is order a test kit, collect the sample at home, and send it in to get the results.
2. Get a professional diagnosis at a clinic
If you would like a more detailed analysis and specialized advice, one option is to undergo genetic testing at a dermatologist’s office or AGA specialist clinic.
3. Use the results to provide appropriate care
The results of a genetic test are merely a guide to your risk. It is important to take appropriate hair care and treatment based on the test results.
References and Evidence
The following research papers provide the latest scientific evidence on genes and hair quality/hair loss risk.
“Relationship between the AR gene and AGA” (Reference link: Research paper link )
“Relationship between EDAR gene and hair thickness” (Reference link: Research paper link )
With these studies in mind, let’s use the latest scientific knowledge to consider measures you can take to maintain healthy hair.
The relationship between genes and grey hair
Genes affect not only hair color, but also the timing and speed of graying. The main cause of graying is a decrease in melanocytes (pigment cells) in the hair roots, and their function is impaired, which is partly determined by genetics.
1. IRF4 gene
The IRF4 gene is related to the production of melanin, and it is known that people with certain variations are more likely to have gray hair. Many Westerners have mutations in this gene, and they tend to have more gray hair at a relatively young age.
2. BCL2 gene
The BCL2 gene plays a role in regulating cell lifespan and is also involved in the maintenance of melanocytes. If there is an abnormality in this gene, pigment cells die early and hair becomes gray more easily.
3. MITF gene
The MITF gene is an important gene that regulates the activity of melanocytes. If this gene does not function normally, the production of melanin, which gives hair color, decreases, making hair more likely to become gray.
Hormonal balance and hair loss
Hormonal imbalance, combined with genetic factors, can accelerate the progression of hair loss. In particular, sex hormones have a large influence and are deeply involved in male pattern baldness (AGA) and female pattern baldness (FAGA).
1. Estrogen and Women’s Hair Health
Estrogen (female hormone) promotes hair growth and extends the lifespan of hair. However, estrogen secretion decreases during menopause, making women more susceptible to female pattern hair loss (FAGA).
2. Testosterone and male pattern baldness (AGA)
When testosterone (male hormone) is converted into DHT (dihydrotestosterone) by the action of 5α-reductase, it has a negative effect on hair roots and causes hair loss. People who are genetically susceptible to the effects of DHT tend to have an accelerated progression of AGA.
3. Thyroid hormone and hair loss
Thyroid hormones play a role in regulating hair growth and metabolism, and hypothyroidism is known to cause thinning hair and increased hair loss.
Stress and gene interactions
Research has shown that stress can be an additional factor that increases your genetic risk of hair loss.
1. Hormonal effects of stress
When you are stressed, excess cortisol (the stress hormone) is secreted, which reduces blood flow and prevents sufficient nutrients from reaching the hair roots, inhibiting hair growth and increasing hair loss.
2. Relationship between genes and stress resistance
The SOD2 and CAT genes have antioxidant properties and play a role in protecting cells from stress. Mutations in these genes may make hair more susceptible to the effects of stress, which may inhibit hair growth.
The relationship between genes and scalp environment
Genes also affect the amount of sebum secreted by the scalp and the susceptibility to inflammation. If the scalp environment deteriorates, people who are genetically at high risk of hair loss may experience more rapid progression of the condition.
1. Gene that regulates sebum secretion (MC5R)
The MC5R gene plays a role in regulating sebum secretion. Mutations in this gene lead to excessive sebum secretion, which can lead to clogged pores and inflammation.
2. Genes that suppress scalp inflammation (IL1B, TNF)
The IL1B and TNF genes are involved in the production of cytokines that cause inflammation. Abnormalities in these genes can lead to chronic inflammation of the scalp, which can cause hair loss.
The future of genetic testing
In recent years, advances in genetic research have led to the development of personalized medicine.
1. Gene-based personalized treatment
In the future, it is believed that it will be possible to prescribe hair growth products and treatments that are optimal for each individual based on the results of genetic testing. For example, approaches such as prescribing 5α-reductase inhibitors for those who are susceptible to the effects of DHT, and antioxidant supplements for those who are vulnerable to oxidative stress, are being considered.
2. Application of gene editing technology (CRISPR)
Using gene editing techniques such as CRISPR-Cas9, new treatments may be developed that correct the genetic mutations that cause hair loss and promote hair growth.
3. Hair loss prediction using AI and big data
Progress is being made in developing systems that utilize AI and big data to combine genetic information with lifestyle data to more accurately predict an individual’s risk of hair loss and suggest optimal preventative measures.
Latest research and evidence (additional)
“The relationship between the IRF4 gene and gray hair” (Reference link: Research paper link )
“Decrease in estrogen and the mechanism of FAGA onset” (Reference link: Research paper link )
“The relationship between stress and risk of hair loss” (Reference link: Research paper link )
“Gene editing technology and the possibility of hair regeneration” (Reference link: Research paper link )
Advances in genetic testing are expected to lead to a greater understanding of hair loss and hair quality, leading to the development of more effective prevention and treatment methods.
The relationship between genes and the hair growth cycle
Hair goes through a cycle of growth, loss, and regrowth (the hair cycle). This cycle consists of three phases: growth (anagen), regression (catagen), and resting (telogen), and the process is controlled by genes.
1. FGF5 gene and length of anagen phase
The FGF5 (fibroblast growth factor 5) gene plays a role in controlling the length of the anagen phase of hair. If there is a mutation, the anagen phase is shortened and hair falls out before it has fully grown, making hair more susceptible to thinning. Conversely, research has shown that suppressing the activity of this gene extends the anagen phase, allowing hair to grow longer and healthier.
2. BMP2 gene and hair follicle regeneration
The BMP2 (bone morphogenetic protein 2) gene is involved in the regeneration of hair follicles. When the activity of this gene decreases, the transition from the resting phase to the anagen phase does not proceed smoothly, increasing the risk of thinning hair and hair loss.
3. Wnt signaling pathway and hair growth
The Wnt signaling pathway plays an important role in activating hair follicle stem cells. Mutations in the WNT10B gene have been shown to reduce the regenerative ability of hair follicles and slow hair growth recovery. Recent studies have suggested that activating this pathway may promote hair follicle regeneration.
New genetic testing to check for inherited risk of alopecia
There are now a range of genetic tests available to assess your risk for hair loss. These tests analyze specific gene mutations and help predict the likelihood of future hair loss.
1. Polygenic Risk Score (PRS)
The latest genetic testing has made it possible to more accurately predict the risk of hair loss by calculating a “Polygenic Risk Score (PRS)” that combines mutations in multiple genes, rather than just a single gene. For example, it has been shown that mutations in both the AR gene (androgen receptor) and the FGF5 gene significantly increase the risk of developing AGA.
2. Genome-wide association study (GWAS)
GWAS (Genome-Wide Association Study) is a method to analyze large-scale genome data and identify genetic markers associated with hair loss risk. Recent research has discovered new genes related to hair loss risk, such as the EDA2R gene (involved in hair follicle development) and the SOX21 gene (involved in regulating the hair cycle).
3. Realization of personalized medicine
With the development of these genetic tests, it is becoming possible to provide customized treatments according to each individual’s genetic risk. For example, finasteride (a drug that suppresses DHT production) is effective for people with high activity of 5α-reductase, while hair growth products containing ingredients that extend the hair cycle are recommended for people with mutations in the FGF5 gene.
Genetics and Nutrition: Preventing Hair Loss Through Diet
Even if you’re genetically at high risk for hair loss, getting the right nutrients can help reduce your risk. In particular, the following nutrients are important for maintaining healthy hair:
1. Relationship between biotin (B7) and the KRT gene
Biotin (vitamin B7) is an important component of keratin (KRT81, KRT83, KRT86) and promotes hair growth. People who have genetically low keratin synthesis can increase hair strength by consuming foods rich in biotin (egg yolks, nuts, bananas, etc.).
2. Iron and the HFE gene
The HFE gene plays a role in regulating the absorption of iron in the body. If there is a mutation in this gene, iron absorption decreases and anemia becomes more likely. Iron deficiency inhibits hair growth and causes hair loss, so it is recommended to actively consume foods rich in iron, such as red meat, spinach, and liver.
3. Zinc and the SOD1 gene
The SOD1 (superoxide dismutase 1) gene has antioxidant properties and protects hair cells from oxidative stress. Zinc is a mineral that supports the function of this enzyme, and if it is lacking, hair becomes brittle. You can replenish zinc by consuming oysters, nuts, and soy products.
4. Omega-3 fatty acids and anti-inflammatory genes (IL10)
The IL10 gene has the function of suppressing inflammatory responses in the body. People who are genetically predisposed to inflammation are more likely to have chronic inflammation of the scalp and progress in hair loss. Omega-3 fatty acids (oil-filled fish, flaxseed oil, walnuts, etc.) have the effect of suppressing inflammation, so it is a good idea to actively consume them.
Ethical issues and future prospects for genetic testing
As genetic testing becomes more widespread, ethical issues have also been raised.
1. Privacy Protection
Genetic information is highly personal data and must be managed appropriately. In particular, careful regulation is required regarding the handling of data obtained by genetic testing companies.
2. Potential for discrimination based on genetic information
In some countries, there are concerns that genetic information may be used to restrict employment or insurance contracts. To prevent this, countries are working to enact “genetic discrimination laws.”
3. Practical application of gene therapy
As gene editing technology advances, it may be possible in the future to develop treatments that can fundamentally reduce the risk of hair loss. However, safety and ethical issues need to be carefully considered.
Advances in genetic research have ushered in an era where hair health can be managed scientifically.
The latest in gene therapy and hair regeneration medicine
In recent years, gene therapy and regenerative medicine have been attracting attention as new treatments for alopecia. Unlike conventional hair growth agents and oral medications, these technologies have the potential to improve the cause of hair loss at the genetic level.
1. Application of gene editing technology (CRISPR-Cas9)
CRISPR-Cas9 is a technology that can precisely edit specific genes, and it may be applied to the fundamental treatment of hair loss. For example, attempts are being made to suppress the progression of AGA by modifying the AR gene, which is sensitive to the effects of DHT (dihydrotestosterone).
2. Hair follicle regeneration treatment using stem cells
Research is being conducted into technologies to generate new hair follicles using iPS cells (induced pluripotent stem cells) and ES cells (embryonic stem cells). In particular, a treatment is being developed to promote natural hair growth by culturing hair follicle stem cells and transplanting them into bald areas.
3. Gene-based growth factor therapy
Research is currently being conducted into a technology that promotes the extension of the hair cycle and the regeneration of hair follicles by injecting growth factors that regulate FGF5 and the Wnt signaling pathway directly into the scalp. This approach is expected to have a greater hair growth effect than existing hair growth products.
Personalized hair care to prevent hair loss
Advances in genetic testing are making it possible to choose hair care products and treatments that are tailored to each individual’s genetic makeup.
1. Customized hair growth products using genetic testing
Currently, some companies have started offering services that provide hair growth products that are individually formulated based on the results of genetic testing. For example, it is possible to provide measures that meet individual needs, such as prescribing a product containing finasteride for people who are susceptible to the effects of DHT, or a product containing antioxidants for people who are sensitive to oxidative stress.
2. AI-based hair care analysis
Hair care diagnostic services that utilize AI are also emerging, and systems are being developed that combine genetic information with lifestyle data to recommend the most suitable shampoos and treatments.
3. Research into the scalp microbiome
Recent research has revealed that the microorganisms living on the scalp (microbiome) affect hair health. Excessive proliferation of certain bacteria and fungi can lead to inflammation of the scalp and hair loss, so the development of hair care products that utilize probiotics (good bacteria) is underway.
The future: Genetic analysis and hair health management
Advances in genetic analysis technology will enable a more scientific approach to hair health management.
Real-time genetic diagnosis Simple genetic tests using smartphones are currently being developed, and it is predicted that in the future it will be possible to check for hair loss risk in real time at home.
Individually optimized hormone therapy It may be possible that hormone balance adjustment therapy will be developed based on genetic analysis of estrogen and DHT secretion levels.
Treating AGA with genetic vaccines Vaccines that correct the genetic mutations that cause AGA are currently being developed, and in the future it may be possible to establish a means of preventing AGA, similar to vaccination.
As genetic research advances, the options available to protect hair health will continue to expand.
Summary
Genetic testing is an important means of scientifically analyzing hair quality and hair loss risk, and selecting the appropriate care and treatment for each individual. Progress is being made in identifying genes involved in hair growth and hair loss, and cutting-edge medical treatments such as CRISPR technology and stem cell therapy are also being researched. In addition, individual optimization of hair care and management of the scalp microbiome using AI are also attracting attention. In the future, it is expected that the development of genetic analysis will make it possible to provide optimal hair loss prevention and treatment for each individual.
