Genes are the blueprints of life and are present in the cells of all living organisms. Understanding how genes work is essential to understanding the mechanisms of health and disease. This article provides a detailed explanation of the structure of DNA, how genetic information is transmitted, and how genes are involved in maintaining life and evolution.
A gene is a specific segment of DNA (deoxyribonucleic acid) that contains the code for making a specific protein within a cell. Genetic information plays an important role in determining the form and function of an organism.
The relationship between DNA and genes
DNA is a molecule with a double helix structure found in the cell nucleus, and is made up of four types of bases: adenine (A), thymine (T), guanine (G), and cytosine (C). This base sequence carries genetic information and directs the synthesis of specific proteins, thereby maintaining life activities.
Number and arrangement of genes
The human genome contains approximately 3 billion base pairs and is estimated to contain approximately 20,000 to 25,000 genes. These genes are stored across 46 chromosomes (23 pairs), and individual characteristics are determined by the genes inherited from both parents.
The double helix structure of DNA, discovered by James Watson and Francis Crick in 1953, supports the mechanism by which genetic information in life is accurately replicated and transmitted to the next generation. DNA strands are linked by base pairs (AT, GC), and this pairing is the key to stably maintaining genetic information.
Mechanisms of gene expression
Genetic information is expressed through the processes of transcription (copying information from DNA to mRNA) and translation (synthesis of protein from mRNA). This process is called the “central dogma” and is considered to be the basic flow of genetic information common to all living organisms.
Epigenetics and DNA regulation
Recent research has shown that even if the DNA sequence does not change, environmental factors and chemical modifications can change gene expression. This field is called “epigenetics,” and it has become clear that stress, diet, and lifestyle habits affect gene function.
Proteins are essential molecules that maintain the structure and function of cells. Many functions that support life, such as enzymes, hormones, and antibodies in the immune system, are controlled by proteins.
Genetic diversity and protein differences
Slight differences in DNA base sequences affect the structure and function of proteins, which in turn leads to differences in individual constitutions, disease risk, drug metabolism ability, and more.
4. Relationship between gene mutations and disease
What is a genetic mutation?
Genetic mutations are changes in the base sequence of DNA. These mutations can occur naturally or can be caused by external factors such as ultraviolet light, radiation, or chemicals.
Genetic disorders
Genetic variations can affect health, and certain gene mutations can cause disease.
BRCA1/BRCA2 gene mutations → increased risk of breast cancer and ovarian cancer
CFTR gene mutations → cause of cystic fibrosis (CF)
HBB gene mutation → Cause of sickle cell disease (SCD)
The relationship between cancer and genes
Genetic abnormalities are involved in the development of cancer. It is known that mutations in tumor suppressor genes (such as p53) cause abnormal cell proliferation, resulting in the formation of tumors. Gene therapy has attracted attention as one cancer treatment, and “personalized medicine,” which provides treatment tailored to each patient, is developing.
CRISPR-Cas9 technology is a revolutionary technology that can precisely cut or modify specific DNA sequences. This technology has the potential to be applied to the treatment of genetic diseases and cancer, and is expected to be used in the medical field.
Human genome analysis and personalized medicine
With the completion of the Human Genome Project, medical treatment utilizing personal genetic information has become a reality. Knowing the risk of certain diseases in advance makes it possible to take appropriate preventive measures.
The relationship between genes and longevity
Research into genes involved in longevity (SIRT1, FOXO3, etc.) is progressing, and methods to slow aging are being developed. It has become clear that lifestyle habits such as diet and exercise affect the expression of these genes.
Genes are the blueprints for living organisms, but their expression is influenced by the environment. It is known that even twins with the same DNA sequence can have differences in their health, personality, and lifespan if they grow up in different environments. The field that studies this interaction between genes and the environment is called “epigenetics.”
DNA methylation and the regulation of gene expression
When a methyl group (CH₃) is added to a specific region of DNA, the expression of that gene can be suppressed. This phenomenon is called “DNA methylation” and is one of the important mechanisms that determine whether genes are turned on or off. For example, it has been confirmed that tumor suppressor genes are abnormally methylated in cancer cells, resulting in reduced expression.
Histone modifications and changes in gene expression
DNA is wrapped around proteins called histones, and chemical modifications of these histones (acetylation, methylation, etc.) control gene expression. For example, it has been shown that stress, diet, and lifestyle habits affect histone modifications, altering gene function.
Examples of how the environment influences genes
Smoking : Toxic substances in tobacco are known to induce DNA methylation, leading to the activation of cancer genes and a decrease in immune function.
Nutrition : Evidence suggests that a mother’s diet during pregnancy may affect gene expression in the fetus, potentially increasing the risk of obesity and diabetes in adulthood.
Stress : It has been reported that severe stress in childhood causes methylation of certain genes, increasing the risk of developing mental illness.
7. The relationship between genes and drugs (pharmacogenetics)
The effects and side effects of drugs vary from person to person, and many of these differences are determined by genes. This field is called “pharmacogenetics,” and it is making a significant contribution to the development of personalized medicine.
Genetic influence on drug metabolism
CYP2D6 gene and effects of analgesics: CYP2D6 is a gene that encodes an enzyme involved in drug metabolism. Variants in this gene can cause individual differences in the effectiveness of analgesics (such as codeine). If metabolism is too fast, the drug may not work as well, and if metabolism is too slow, side effects may be severe.
The CYP2C19 gene and antithrombotic drugs The metabolism of antithrombotic drugs such as prasugrel and clopidogrel is affected by the CYP2C19 gene.It has been reported that people with certain gene mutations have a reduced drug effect and an increased risk of cardiovascular events.
TPMT Gene and Cancer TreatmentVariants in the thiopurine methyltransferase (TPMT) gene alter the rate at which some cancer drugs (mercaptopurine) are metabolized. Genetic testing is recommended because patients with certain genotypes may experience serious side effects when given normal doses.
Advances in pharmacogenetics have made it possible to select drugs based on individual genetic characteristics, leading to safer and more effective treatments.
Research is ongoing into the relationship between genes and lifespan, and it has been found that certain genes are involved in longevity.
Genes involved in longevity
FOXO3 gene : People with certain variants of this gene have been reported to have a lower risk of cardiovascular disease and a tendency to live longer.
SIRT1 gene : This gene is one of the sirtuin genes, and it suppresses cellular aging and regulates energy metabolism. It has been suggested that resveratrol (a polyphenol found in red wine) activates this gene.
KLOTHO gene : It may play a role in preventing age-related cognitive decline, and people with certain variants may have a lower risk of dementia.
Lifestyle and gene interactions
Even if you have genes related to longevity, if you live an unhealthy lifestyle, the effects will not be fully realized. Conversely, it is believed that by practicing appropriate lifestyle habits, you can make the most of your genetic longevity factors.
Diet : Calorie restriction may activate the SIRT1 gene and slow aging.
Exercise : It has been suggested that moderate exercise increases the activity of the FOXO3 gene and extends healthy lifespan.
Stress management : Chronic stress can affect DNA methylation and accelerate aging, so proper stress management is recommended.
Advances in genetic research into longevity are helping to shed light on the mechanisms of aging, and in the future, new medical technologies may emerge that can slow down aging.
9. The relationship between genes and the immune system
Our immune system works to protect the body from pathogens, and its function is closely related to genes. The strength of an individual’s immune system and their susceptibility to infectious diseases vary depending on genetic factors.
HLA genes and immune responses
Human leukocyte antigen (HLA) genes play a key role in immune cell recognition of pathogens, and different HLA variants affect disease susceptibility and autoimmune disease risk.
HLA-B27 : People with this gene have been reported to be at higher risk of ankylosing spondylitis and psoriatic arthritis.
HLA genes and COVID-19 : Research suggests that certain HLA types may affect the risk of infection and severity of COVID-19.
Interferon genes and viral defense
Interferons are proteins that trigger a defense response against viral infections, but individuals vary in their ability to produce them. Mutations in certain interferon genes may increase susceptibility to viral infections, such as HIV and influenza.
It is known that allergic tendencies are also influenced by genetic factors.
IL-4 gene and asthma
IL-4 is a type of cytokine involved in regulating the immune system. It has been reported that certain mutations in the IL-4 gene enhance allergic reactions and increase the risk of asthma and hay fever.
Filaggrin (FLG) gene and atopic dermatitis
The FLG gene is involved in the skin’s barrier function, and mutations in this gene reduce the skin’s moisturizing function, increasing the risk of atopic dermatitis.
Brain function and mental health are also influenced by genes.
Serotonin transporter gene (5-HTTLPR) and stress resistance
Serotonin is a mood-stabilizing neurotransmitter, and variants of the serotonin transporter gene (5-HTTLPR) affect stress tolerance.
S type (shortened type) : Sensitive to stress and prone to anxiety.
L type (long type) : Tends to have high stress tolerance and an optimistic temperament.
The BDNF gene and memory
The brain-derived neurotrophic factor (BDNF) gene is involved in the growth and maintenance of nerve cells and influences memory and learning ability. Individuals with certain variants have been reported to have a lower tolerance to stress and a higher risk of depression.
Sleep patterns and quality are also influenced by genes.
The DEC2 gene and short sleepers
People with certain mutations in the DEC2 gene are said to be able to get enough rest with less sleep (4-6 hours) than the average person.
CLOCK gene and circadian rhythm (body clock)
The CLOCK gene plays a role in regulating circadian rhythms. Mutations in this gene have been shown to lead to a nocturnal lifestyle and increase the risk of insomnia.
Surprisingly, genes may also influence love and partner selection.
HLA genes and opposite-sex attraction
HLA genes are part of the immune system, but they are also thought to influence olfactory preferences when choosing a mate.
People tend to prefer the body odor of the opposite sex who has a different HLA type than themselves.
This is thought to be a biological mechanism for producing genetically diverse offspring.
The oxytocin receptor gene (OXTR) and affection
Oxytocin, also known as the “love hormone,” plays an important role in building intimate relationships. It has been suggested that differences in the OXTR gene may affect the strength of affection and the sensitivity to trust.
14. The relationship between genes and athletic ability
Athletic ability is greatly influenced by training and environmental factors, but genetic factors are also known to play a role.
Muscle fiber type and the ACTN3 gene
The ACTN3 gene is involved in the formation of fast-twitch muscles (muscles that exert explosive force). There are three variants of this gene, which are thought to affect athletic ability:
RR type : Contains many fast-twitch muscle fibers and is suitable for explosive sports such as sprinting and weightlifting.
RX type : A balance of fast and slow twitch muscles, making it suitable for a variety of sports.
XX type : Has a lot of slow-twitch muscle fibers, making it suitable for endurance sports such as marathons and cycling.
According to data from Olympic athletes, sprinters tend to have RR blood type, while endurance athletes tend to have XX blood type.
Endurance and the PPARGC1A gene
The PPARGC1A gene promotes mitochondrial production and improves endurance, and individuals with specific variants of this gene have been shown to perform better in endurance sports.
15. The relationship between genes and social behavior
Genes may also influence the formation of human social behavior and personality.
The MAOA gene and aggression
The MAOA (monoamine oxidase A) gene is involved in the breakdown of the neurotransmitters serotonin and dopamine. It has been suggested that mutations in this gene may affect the intensity of aggression and impulsivity.
Low activity type (MAOA-L) : Tends to have high levels of aggressive behavior and impulsivity.
High activity type (MAOA-H) : Easier to control emotions and has high social adaptability.
However, environmental factors also have a significant influence, so genes alone cannot determine an individual’s personality.
The AVPR1A gene and empathy
The AVPR1A gene encodes a receptor for the hormone vasopressin (antidiuretic hormone), which is thought to be involved in empathy and social behavior.
People with certain variants tend to be more cooperative and empathetic.
People with another variant tend to behave more selfishly in interpersonal relationships.
16. The relationship between genes, creativity, and intelligence
Intelligence and creativity are also thought to be formed by the interaction of genetics and the environment.
CHRM2 gene and intelligence quotient (IQ)
The CHRM2 gene is involved in neurotransmission and has been linked to intelligence quotient (IQ), with individuals with certain variants potentially exhibiting superior learning and memory abilities.
The DARPP-32 gene and learning ability
The DARPP-32 gene is involved in dopamine signaling and is known to influence learning and the reward system, and mutations in this gene may be associated with poor math and language skills.
The COMT gene and creativity
The COMT (catechol-O-methyltransferase) gene is involved in dopamine metabolism and is thought to influence creativity and problem-solving abilities.
Val/Val type : Highly focused and good at logical thinking.
Met/Met type : Excellent at flexible thinking and creativity.
This genetic influence, combined with environmental factors, can make a big difference in how an individual performs.
Advances in genetic research are bringing about major changes in our lives and society, but at the same time, ethical issues are also emerging.
The risk of genetic discrimination
There is a risk of “genetic discrimination” that restricts employment and insurance coverage based on genetic information. In the United States, the Genetic Information Nondiscrimination Act (GINA) has been enacted, prohibiting discrimination based on genetic information.
Data Privacy Issues
As the number of companies offering genetic testing increases, concerns are growing about whether personal genetic information is being managed appropriately. If genetic information were to be leaked, it could affect the privacy of family members, so strict data management is required.
Ethical issues surrounding gene editing
With the development of CRISPR technology, gene editing is becoming a reality, but the following ethical issues have been raised:
Designer Babies : The pros and cons of editing specific genes to create children with desirable traits.
Unintended consequences : Gene editing may pose unintended health risks.
Widening social divide : There is a possibility that new social divides will emerge between those who have access to gene editing and those who do not.
In order to solve these problems, the establishment of international rules and regulations is required.
18. The future of genetic research and its impact on society
Advances in genetic research have the potential to change medical care, lifestyles, and even society as a whole. How we utilize genetic information in the future will have a major impact on our lives.
Combining AI and genetic analysis
Advances in artificial intelligence (AI) have made it possible to analyze vast amounts of genetic data much faster. AI opens up new possibilities, including:
Early detection of disease : Predicting the risk of developing cancer, Alzheimer’s disease, and other diseases at the genetic level, leading to early diagnosis.
Development of personalized medicine : It will become possible to select the most appropriate medicines and treatments based on individual genetic characteristics.
Accelerating drug development : Using genetic data to speed up the development of more effective treatments.
In the future, services may emerge that utilize genetic information to suggest optimal lifestyles and career paths for individuals. For example, the following uses are possible:
Optimizing diet and exercise : Based on the results of genetic testing, we design diet and exercise programs tailored to each individual’s constitution.
Diagnosing occupational aptitude : It may become possible to diagnose occupational aptitude based on genetic tendencies.
Improving mental health care : Developing stress management methods that take genetic factors into account.
Social challenges of genetic technology
While advances in genetic technology bring many benefits, they also raise ethical and social issues.
Widening genetic disparities : If only those who can afford it can receive advanced genetic medicine, social inequality could widen.
Risk of misuse of genetic data : The risk that misuse of genetic information could lead to discrimination and prejudice.
Need for regulation : Clear rules regarding gene editing and data use are needed.
We will need to continue to closely monitor how advances in genetic research will affect society.
Genes are important factors that influence all aspects of our lives, including our health, personality, athletic ability, and disease risk. Recent research has revealed links between genes and immunity, sleep, mental health, creativity, and more. Furthermore, advances in gene editing using CRISPR technology and genome analysis using AI are expanding the possibilities for personalized medicine and preventive medicine.
However, advances in genetic technology also bring with them ethical and social challenges. As science advances, there will likely be a need for deeper discussion on how to utilize genetic information in a fair and safe manner.
