DNA, disease and location are connected- Know how? - Seeker's Thoughts

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DNA, disease and location are connected- Know how?

In the journal of Trends in Immunology , researchers describe how ancestral origins impact the likelihood that people of African or Eurasian descent might develop immune-related diseases.

Some of the same mutations allowing humans to fend off deadly infections also make us prone to certain inflammatory and autoimmune disease, such as Crohn’s diseases. The author also share evidence that the human immune system is still evolving depending on a person’s location or lifestyle.

Human immune system touches almost every aspect of their health, so it’s no surprise that so many diseases have their root in an unbalance in that system.

What are immune related diseases?

There are more than 80 different diseases and more than 100 different cancers that’s afflict people around the world, and many more disease that involve the immune system.

Immune system disorder cause abnormally low activity or over activity of the immune system. In case of immune system over activity, the body attacks and damages its own tissue which is also called autoimmune diseases. Immune deficiency diseases decrease the body’s ability to fight invaders, causing vulnerability to infections.

In response to an unknown trigger, the immune system may begin producing antibodies that instead of fighting infections, attack the body’s own tissue. Treatment for autoimmune diseases generally focuses or reducing immune system activity.

There are different diseases related to immune system, but some of them are as follow---

Rheumatoid arthritis. The immune system produces antibodies that attach to the linings of joints. Immune system cells then attack the joints, causing inflammation, swelling, and pain. 

Systemic lupus erythematous (lupus). People with lupus develop autoimmune antibodies that can attach to tissues throughout the body. The joints, lungs, blood cells, nerves, and kidneys are commonly affected in lupus. 

Inflammatory bowel disease (IBD). The immune system attacks the lining of the intestines, causing episodes of diarrhoea, rectal bleeding, urgent bowel movements, abdominal pain, fever, and weight loss. Ulcerative colitis and Crohn's disease are the two major forms of IBD. 

Multiple sclerosis (MS). The immune system attacks nerve cells, causing symptoms that can include pain, blindness, weakness, poor coordination, and muscle spasms.4

Type 1 diabetes mellitus. Immune system antibodies attack and destroy insulin-producing cells in the pancreas. By young adulthood, people with type 1 diabetes require insulin injections to survive.

Guillain-Barre syndrome. The immune system attacks the nerves controlling muscles in the legs and sometimes the arms and upper body. Weakness results, which can sometimes be severe.

Chronic inflammatory demyelinating polyneuropathy. Similar to Guillain-Barre, the immune system also attacks the nerves in CIDP, but symptoms last much longer. About 30% of patients can become confined to a wheelchair if not diagnosed and treated early 

Psoriasis. In psoriasis, overactive immune system blood cells called T-cells collect in the skin. The immune system activity stimulates skin cells to reproduce rapidly, producing silvery, scaly plaques on the skin. 

Graves' disease. The immune system produces antibodies that stimulate the thyroid gland to release excess amounts of thyroid hormone into the blood (hyperthyroidism). Symptoms of Graves' disease can include bulging eyes as well as weight loss, nervousness, irritability, rapid heart rate, weakness, and brittle hair.  

Hashimoto's thyroiditis. Antibodies produced by the immune system attack the thyroid gland, slowly destroying the cells that produce thyroid hormone. Low levels of thyroid hormone develop (hypothyroidism), usually over months to years. Symptoms include fatigue, constipation, weight gain, depression, dry skin, and sensitivity to cold. 

Myasthenia gravis. Antibodies bind to nerves and make them unable to stimulate muscles properly. Weakness that gets worse with activity is the main symptom of myasthenia gravis. 

Vacuities. The immune system attacks and damages blood vessels in this group of autoimmune diseases. Vacuities can affect any organ, so symptoms vary widely and can occur almost anywhere in the body. 

How immune- related diseases are connected to African or Eurasian descent?

Author Jorge Dominguez-Andres says, in the past, people’s lifespan were much shorter, so some of these inflammatory and autoimmune diseases that can appear in the second half of life were not so relevant.

One of the body’s best defences against infectious diseases is inflammation. Dominguez-Andres and senior author Mihai Netea and other evolutionary biologist, complied data from genetics, immunology, microbiology and virology studies and identified how the DNA from people within different communities commonly infected with bacterial or viral diseases was altered, subsequently allowing for inflammation.

While these changes made it more difficult for certain pathogens to infect these communities, they were also associated with the emergence over time of new inflammatory diseases such as Crohn’s diseases lupus, and inflammatory bowel disease.

"There seems to be a balance. Humans evolve to build defences against diseases, but we are not able to stop disease from happening, so the benefit we obtain on one hand also makes us more sensitive to new diseases on the other hand,"

Today, we are suffering or benefiting from defences built into our DNA by our ancestors' immune systems fighting off infections or growing accustomed to new lifestyles."

African connection

For instance, the malaria parasite plasmodium sp. has infected African populations for millions or years. Because of this evolutionary processes have selected people with DNA that favors resistance to infections by causing more inflammation in the body. In doing so, this has also contributed to making modern Africans prone to developing cardiovascular diseases, such as atherosclerosis, later in life.

Eurasians connection

Author also write about how the early-human ancestors of Eurasians lived in regions still inhabited by Neanderthals and interbred.

Today people with remainders of Neanderthal DNA can be more resistant against HIV-1 and 'staph’ infections, but are also more likely to develop allergies, asthma and hay fever.

The negative side effects of changes in each population's immune systems are a relatively recent finding

According to the authors they know a few things happening at the genetic level in our ancestry, but they need more powerful technology. So, next generation sequencing is bursting now and allowing us to study the interplay between DNA and host responses at much deeper levels.

These technologies are also revealing how our immune systems are evolving in real time because of modern lifestyle changes.

 African tribes that still engage in hunting have greater bacterial gut diversity than urbanized African-Americans that eat store-bought foods. Also, changes in hygiene patterns seen in the last two centuries have improved sanitation, drinking water, and garbage collection, and have led to reduced exposure to infectious pathogens relative to previous times. As humans move toward processed foods and stricter hygiene standards, their bodies adapt by developing what researchers call "diseases of civilization," such as type 2 diabetes.

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