World DNA Day 2023: Human DNA Is Prone To Damage And Disease. Experts Explain Why

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms, and stores genetic information in the form of codes made up of four chemical bases each.

World DNA Day is observed every year on April 25 to commemorate the completion of the Human Genome Project, and the anniversary of the discovery of the double helix model of DNA. The 108th Congress passed resolutions designating April 25 as DNA day, and since then, it has been celebrated worldwide. The aim of the day is to educate the world about the latest advances in genomic research.

On April 25, 1953, American biologist James Watson and English physicist Francis Crick published a paper titled "A Structure for Deoxyribose Nucleic Acid" in the journal Nature, explaining the double helix structure of DNA. 

The Human Genome Project was a landmark global scientific effort started in 1990 with the aim of generating the first sequence of the human genome. By 2003, about 92 per cent of the genome had been decoded under the Human Genome Project. By 2022, the remaining eight per cent was sequenced. 

DNA, which stands for deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms, and stores genetic information in the form of codes made up of four chemical bases each. More than 99 per cent of the three billion bases found in human DNA are the same in all people. 

DNA can replicate and make copies of itself. 

How human DNA is prone to disease and damage

A lesser known fact about DNA is that the hereditary material is prone to damage from interaction with various chemicals such as free radicals produced from metabolism, and environmental agents such as ultraviolet radiation. Sometimes, these damages can lead to mutation, and eventually disease. Skin cancer, which is caused by excessive radiation to ultraviolet radiation from sunlight, is an example of the link between environmental-induced DNA damage and disease. DNA damage can also lead to genetic diseases.

“DNA is indeed susceptible to disease and damage, as it can be affected by various factors like exposure to radiation, toxins, chemicals, and errors during replication. The result of such damage can be mutations, which can cause genetic diseases and cancer,” Dr. Vidya Jha, Associate Professor and Head, Cytogenetics, Deputy Medical Superintendent, Amrita Hospital, Kochi, told ABP Live.

Dr Jha explained that DNA damage can occur despite defence mechanisms having the ability to protect the DNA. Certain factors such as exposure to ultraviolet radiation from sunlight and exposure to tobacco smoke can increase the risk of skin cancer and lung cancer, respectively, both of which are results of DNA damage.

“Although there are defence mechanisms that have evolved to safeguard DNA from damage and repair injury, DNA damage can still occur, and some factors can increase the likelihood of such damage and disease. For instance, exposure to ultraviolet (UV) radiation from the Sun can heighten the risk of skin cancer, while exposure to tobacco smoke can increase the likelihood of lung cancer, both of which are consequences of DNA damage,” Dr Jha said.

DNA damage can lead to mutations, which in turn result in uncontrolled cell growth and division, and ultimately, cancer. Some of the genetic diseases caused by DNA mutations include cystic fibrosis, a disease characterised by the buildup of thick, sticky mucus which can damage the body’s organs; sickle-cell anaemia; and Huntington’s disease, a disorder that causes neurons in parts of the brain to break down and die. DNA mutations can also result in neurodegenerative diseases.

“Human DNA is susceptible to several diseases and damage. For instance, DNA damage can cause mutations that result in uncontrolled cell growth and division, leading to the development of cancer. Additionally, mutations in DNA can cause genetic diseases such as cystic fibrosis, sickle-cell anaemia, and Huntington's disease. DNA damage can accumulate over time, contributing to the ageing process. Mutations in DNA can also lead to neurodegenerative diseases like Alzheimer's, Parkinson's, and Huntington's disease,” Dr Jha said.

She also said that alterations in the DNA can result in the immune system attacking the body's tissues, leading to autoimmune diseases such as lupus, multiple sclerosis, and rheumatoid arthritis.

Lupus is an autoimmune disease that occurs when the body’s immune system attacks its own cells, leading to inflammation. 

Multiple sclerosis is a disabling autoimmune disorder of the brain and spinal cord in which the immune system attacks the myelin sheath or the protective sheath covering nerve fibres, and causes communication problems between the brain and the rest of the body.

Rheumatoid arthritis is an autoimmune disease and a form of arthritis characterised by pain, swelling, stiffness and loss of function of the joints.

According to experts, DNA diseases can also be caused by inherited genetic alterations, which may occur as a result of environmental factors, or due to other genetic factors. While the human body has certain systems to repair damaged DNA and avoid mutations, they are not always successful.

“Human DNA is prone to diseases and damage. DNA is continually exposed to different variables such as radiation, toxins, and oxidative stress, all of which can cause DNA molecule damage. Some diseases are caused by inherited genetic alterations, while others are caused by environmental causes or a combination of both. Fortunately, the human body has a number of systems in place to repair damaged DNA and avoid mutations. These systems, however, are not always totally successful, and DNA damage can accumulate over time, increasing the risk of illness and other health concerns,” Dr Babina NM, Chief Medical Officer, Jindal Naturecure Institute, Bangalore, told ABP Live.

Lifestyle variables and innate genetic predisposition may make DNA vulnerable to disease and damage. Sometimes, mutations are inherited or acquired due to exposure to carcinogens. Inherited mutations can lead to different genetic disorders.

Ageing also makes DNA more susceptible to damage from external stressors.

"Human DNA is vulnerable to a wide range of diseases and damage as a result of environmental exposures, lifestyle variables, and innate genetic predisposition. One of the most serious diseases caused by DNA damage is cancer. Cancer is caused by DNA mutations that induce uncontrolled cell growth and division. These mutations can be inherited or acquired as a result of exposure to carcinogens such as tobacco smoke, radiation, and certain chemicals. Another problem associated with DNA damage is ageing. As we become older, our DNA becomes more vulnerable to damage from external stressors including UV radiation and oxidative stress. This can lead to age-related disorders such as Alzheimer's and Parkinson's. Genetic disorders can be caused by inherited mutations in DNA that affect various cellular processes. Sickle cell anaemia is the main disease caused by genetic DNA damage,” Dr NM said.

The damaging agents which attack DNA can be categorised into intrinsic and extrinsic factors. Ultraviolet radiation, ionising radiation, chemical agents and viruses are extrinsic factors, while free radicals generated inside the body as a result of metabolism are intrinsic factors.

“The genetic code in human DNA is constantly being attacked by intrinsic and extrinsic damaging agents, such as ultraviolet radiation or ionising radiation (IR), chemical agents, and viruses. These agents lead to mutations which have deleterious consequences and can cause genetic diseases, which are inherited or occur sporadically, such as cystic fibrosis, sickle cell anaemia, and Huntington's disease. DNA damage can accumulate over time due to ageing and exposure to environmental factors, leading to a higher risk of developing cancer,” Dr Preet Pal Thakur, Co-Founder Glamyo Health, told ABP Live.

Dr Thakur explained that genetic disorders are caused by DNA mutations, cancer is caused by mutations that disrupt the normal cell-cycle, and ageing-related disorders such as dementia are also a result of DNA damage and mutations.
“Genetic disorders such as cystic fibrosis, sickle cell anaemia, and Huntington's disease are caused by mutations in DNA. Cancer can also result from DNA damage due to mutations that disrupt the normal cell cycle, leading to uncontrolled growth and proliferation. Ageing-related conditions such as dementia and Alzheimer's disease have also been linked to DNA damage and mutations,” Dr Thakur said.

Dr Thakur concluded that the susceptibility of human DNA to diseases and damage is due to its complex structure and function, as well as exposure to internal and external factors throughout life.