Types of Genetic Disorders: Definitions & Symptoms

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  • 0:30 Cystic Fibrosis & Sickle Cell
  • 2:51 Other Disorders
  • 5:01 Cancer
  • 6:28 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
Cystic fibrosis, Huntington's disease, Tay-Sachs disease, sickle cell disease, Down syndrome, and cancer all have something in common. They are all genetic disorders, and we will discuss why they may occur and what problems they might cause.

Genetic Disorders & Errors

Genetic disorders are types of diseases that occur as a result of an abnormality in our genetic code - the code that makes us who we are. If it is a bit off or massively messed up, then run-time errors result, causing a person with the genetic disorders a whole slew of problems.

This lesson will point out for you some very well-known genetic disorders, why they occur, and what that results in, in terms of errors in function of our body.

Cystic Fibrosis and Sickle-Cell Disease

One very well-known and talked about genetic disorder is known as cystic fibrosis, a genetic disease that occurs as a result of a mutation in the CFTR gene. A mutation in this gene causes normally thin and watery secretions in your lungs and pancreas to become very thick and sticky, like molasses.

This causes the airways of the lungs to become clogged with abnormal mucus. The thick mucus results in difficulty breathing and predisposes a person to bacterial infections in the lungs. Because the ducts of the pancreas, an organ that makes digestive juices, are also clogged up, people suffer from malnutrition, because they cannot properly digest and absorb their food.

Cystic fibrosis is like having the city streets, like airways and ducts in your body, chock full of molasses. It will be very difficult to move through them, like it is difficult for air and digestive juices to move through the clogged passageways as well.

Another very famous genetic disorder is called sickle cell disease, and it is a blood disorder that results in abnormally shaped red blood cells. Normally, red blood cells, the guys that carry oxygen throughout your body, have a nice round shape. But in sickle cell disease, the red blood cells look like a sickle, as in a hammer and sickle. Or, you can think of them as having a crescent shape.

These abnormal red blood cells do not live for very long, about 10-20 days, as opposed to 120 days for a normal red blood cell. Because the number of dying red blood cells outpaces the amount that can be produced, a person becomes anemic, or deficient in red blood cells. This is why sickle cell anemia is just one problem associated with sickle cell disease, and it leads to a feeling of fatigue, since your body's tissues don't get enough energy-giving oxygen delivered to them.

Just think of a sickle cell as a truck transporting energy drinks and food throughout a country. If the trucks break down days after leaving an assembly plant, there won't be a big enough supply of working trucks, and this causes fewer trucks to be on the road, which means there's less food being delivered to stores. With sickle cell disease, your body isn't getting nutrition very efficiently, and that means you are hungry more often and as a result feel kind of tired most of the time.

Down Syndrome, Tay Sachs, & Huntington's Disease

While sickle cell anemia implies a lack of something, a lack of red blood cells, some genetic disorders have too much of something. Namely, in Down syndrome, people are born with one extra copy of chromosome 21 and therefore have three, as opposed to two, chromosomes.

Down syndrome is a condition that results in mental disabilities, a small head, short neck, and flattened facial features. Around half of all people born with Down syndrome also have a heart defect. Many others are predisposed to all sorts of other problems, like an underactive thyroid gland and gastrointestinal disease.

Children born with Down syndrome typically live longer than those that are born with another terrible genetic disorder, known as Tay-Sachs disease. This is a disorder where a defective gene on chromosome 15 causes the destruction of neurons (or nerve cells) in the brain and spinal cord as a result of fatty substance accumulation. Such a problem will lead to weak muscles, an inability to sit or crawl, seizures, vision and hearing loss, in addition to paralysis and death by age 4 or 5.

The destruction of the nerve cells is akin to having the electrical circuitry in your phone, fridge, or car completely destroyed. None of these things can function without all that wiring, and that is similar to why a person's body similarly shuts down under the influence of Tay-Sachs disease.

Another genetic disorder that affects neurons is called Huntington's disease, a disorder that causes the breakdown (or degeneration) of nerve cells in the brain due to a mutation in the HTT gene. Unlike Tay-Sachs disease, which causes problems early in life, Huntington's disease usually causes symptoms around age 40. People who have this problem have trouble moving, due to involuntary jerking or muscle rigidity. They also cognitive disorders, such as difficulty planning their tasks or learning new information. Psychiatric problems may also occur, such as depression or obsessive-compulsive disorder.

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