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10 Most Common Mutations in Humans

by David Long
fact checked by Rachel Jones

Nearly all living organisms (including us) have DNA in almost every cell in their bodies. Different sections of DNA carry different pieces of information, called genes, which are passed down from parents to children. Genes govern everything from the color of your eyes to the size of your feet.

Within a cell, there is a structure called a chromosome, which contains proteins and DNA. There are normally 23 pairs of chromosomes. Mutations appear when there is a change in the sequence of DNA. Mutations are essential because, without them, evolution can’t take place.

Mutations are caused by three things: 1) an error in replication when cells divide, 2) exposure to chemical or physical agents such as radiation, tobacco, or chemicals, and 3) viral infections.

Related: 10 Scary Genes We Can Inherit From Our Parents

10 Down Syndrome

Do All People With Down Syndrome Think The Same? | Spectrum

In the United States, around 6,000 babies a year are born with Down Syndrome. Usually, a baby is born with 46 chromosomes—23 from the mother and 23 from the father. A baby with Down Syndrome has an extra copy of Chromosome 21, which affects how the baby’s body and brain develop.

People with Down Syndrome might have similar behavior patterns and share some physical characteristics, but they are as distinct from each other as any other person is. While it is true that people with Down Syndrome may have lower IQs than the general population, this also varies from person to person.

Down Syndrome people tend to have a shorter life expectancy than the general population, but this is increasing with time. The leading causes of death are respiratory illness or congenital heart problems, though why they seem to be more prone to these ailments is not entirely clear.

9 Cystic Fibrosis

Tara’s Story – Living With Cystic Fibrosis

Cystic fibrosis is an inherited disorder. The disorder causes severe damage to the digestive system, lungs, and other organs. It affects the cells that produce digestive juices, sweat, and mucus. For healthy people, these liquids act as slick lubricants. But in people with cystic fibrosis, these liquids are thick and sticky. Because of these characteristics, the liquids block passageways, tubes, and ducts in the lungs and pancreas.

In the United States, some 30,000 people live with this condition. It is a progressive disease that requires daily care and causes early mortality, though life expectancies are continuing to increase.

Scientists identified cystic fibrosis as a separate disease in 1938. At that time, patients who had it could expect to live for just six months after their diagnosis. While there is no cure, there are various medications and therapies available that help alleviate symptoms.

8 Sickle Cell Anemia

Sickle cell anemia – causes, symptoms, diagnosis, treatment & pathology

Around 100,000 Americans suffer from sickle cell anemia. This disease is most common among people of African, Mediterranean, or Middle Eastern descent. Currently, the only cures are bone marrow or stem cell transplants.

A red blood cell is round and lives for about 120 days. When people suffer from sickle cell anemia, the blood cells are sickle-shaped and die within 20 days. Because of their shape, affected cells become sticky and rigid and block blood flow. These cells are much less efficient at transporting oxygen around the body.

Symptoms usually appear when the affected person is around six months old. Symptoms are due to inefficient oxygen supplies or blood flow blockage and may include any of the following:

  • Anemia
  • Pain
  • Swelling of the hands and/or feet
  • Frequent infections
  • Delayed puberty and growth
  • Problems with vision

Treatments such as blood transfusions can relieve pain and prevent some of the complications that may occur.

7 Huntington’s Disease

Living with Huntington’s disease

This disease can appear at any time in a person’s life, although it most commonly shows up when people are in their 30s or 40s. Huntington’s disease involves a degeneration of the cells in the brain, and most sufferers die within 15-20 years of their diagnosis.

In 1872, George Huntington first identified the disease in residents in East Hampton, Long Island. The disease occurs because of a mutation in a gene located on Chromosome 4.

Huntington’s causes a wide range of symptoms. There may be disorders in movement, cognition, or psychiatric problems. There is no cure for Huntington’s disease and no way to halt its progress. The best that clinicians can do is use treatment to reduce some of the problems associated with it.

6 Alzheimer’s Disease

Alzheimer’s Is Not Normal Aging — And We Can Cure It | Samuel Cohen | TED Talks

An astonishing six million Americans suffer from Alzheimer’s disease or related dementia.

The disease is a progressive neurological disorder in which the brain shrinks and cells die. It is the most typical cause of dementia. Most researchers believe that proteins attack the brain, although some Alzheimer’s cases are caused by a gene mutation passed from parent to child. One of these proteins, amyloid, causes plaque to build up around brain cells. The other, tau, forms tangles within the brain cells.

Aducanumab, a human antibody, is currently the only approved medication that can combat Alzheimer’s.

There is no certain way to avoid getting Alzheimer’s, but some research suggests that lifestyle choices may play an active part in helping to prevent or delay the onset of Alzheimer’s. Regular exercise, a healthy diet, and doing things to mentally challenge yourself may all help.

The brain is an organ, and all organs need nutrients and exercise. To help prevent this disease, consider eating a well-balanced lunch, going for a walk, then doing a crossword puzzle.

5 Obesity

Is obesity in our genes? Study strengthens genetic link to body size

Some studies suggest that 70 million adults in the United States are obese. It is easy to dismiss obesity as a direct result of people making wrong lifestyle choices.

However, things are not as simple as that. Obesity is the result of an imbalance caused by people ingesting more calories than they burn. The excess is converted into fat. The brain regulates food intake by responding to signals. Both signals and the responses depend on genes, which means that if the genes have mutated, they may warp the signals.

Fifty different genes appear to be associated with obesity, and researchers have found that inherited factors have more influence than the environment. People are not choosing to be obese; rather, their brains are receiving the wrong signals, and genetic mutations are responsible for the errors.

People can learn to override the mistaken signals, but it can be difficult. In some cases, clinicians may have to treat the disease with drastic surgery to alter the digestive system. Obesity increases the risk of diabetes, heart disease, stroke, and other ailments.

4 Diabetes

Genetics and Diabetes: Who Is Predisposed?

Type 2 diabetes causes the level of glucose in the blood to rise. Symptoms include tiredness, frequent need to urinate, and excessive thirst. Although diabetes is often linked to being inactive and/or overweight, it can also result from an inherited genetic mutation.

Although lifestyle may play an important part, if a doctor diagnoses diabetes, it is probably that a family member has had it.

Inherited or not, you can reduce your chances of getting diabetes by living a healthier life. Exercise regularly and eat a healthy diet.

There is no cure for type 2 diabetes, but the condition can be managed, and those affected can lead a normal life as long as they keep an eye on their condition.

3 Cancer

What Is Cancer? What Causes Cancer & How Is It Treated?

Cancer is the most common mutation in humans by far. Nearly 40% of the population will get cancer at some time in their lives, and in the USA, nearly 1.6 million people are diagnosed with it each year.

Cells become cancerous because of mutations in their genes. The cells divide uncontrollably and spread, rather than dying once the body has replaced the necessary amount of cells.

Cancer can be caused by many things, such as environmental factors, lifestyle choices, and exposure to radiation and specific chemicals. The most common cancers in 2020 were breast, lung, and colon/ rectum cancers.

2 Hemochromatosis

Understanding Haemochromatosis

When someone has problems with their iron levels, it’s typically because they have a deficiency. But the opposite problem can also occur: hemochromatosis. This is caused by a mutation in the HFE gene, resulting in an inability to get rid of excess iron.

Too much iron stored in the body can cause severe organ damage, especially to the liver. Men are more likely than women to suffer from hemochromatosis, which is more common in people of Northern European descent.

Treatments include removing blood from the body and avoiding foods with iron. Hemochromatosis requires constant monitoring, as patients often show no symptoms.

1 Lactose Tolerance

The Evolution of Lactose Tolerance — HHMI BioInteractive Video

Mammals stop drinking milk when they have finished weaning, but most humans don’t. This is because a mammal stops producing an enzyme called lactase and can no longer digest milk once it can ingest other foods. A mutation in humans, which seems to have risen after domesticating animals about 4,000 years ago, means that most of us continue to produce lactase and can enjoy a wide range of dairy products.

Today, about 50% of Americans are estimated to be lactose intolerant. Symptoms typically occur within 30 minutes to two hours after eating/ drinking food with lactate and may include:

  • Nausea
  • Gas
  • Diarrhea
  • Stomach cramps
  • Bloating

Treatments for lactose intolerance are lactate tablets or drops, which break down the lactose in the body. Avoid medications that contain lactate and foods that contain milk or dairy.

fact checked by Rachel Jones