Examining Some Genetic Diseases - dummies

Examining Some Genetic Diseases

Genetic diseases are the result of an abnormal pattern in the DNA of an individual. These diseases are inherited, though some individuals are only carriers and not sufferers. Recently, quite a bit of research has been done to determine the genetic pattern that causes the disease and ways to detect the probability of passing on the disease to offspring. However, methods of treatment for most of these diseases are limited. In this article, we briefly examine a few of the more well-known genetic diseases.

Sickle cell anemia

Sickle cell anemia is a disease of the blood’s hemoglobin, a component of red blood cells. Sickle cell anemia is the result of the substitution of the amino acid valine (non-polar) for glutamic acid (polar). The condition especially affects those whose ancestors came from Africa, South America, Cuba, Saudi Arabia, and a few other countries. In the United States, it affects about 72,000 people.

Hemoglobin is responsible for carrying oxygen from the lungs to the cells. Defective sickle cell hemoglobin molecules clump together, causing the red blood cells to assume a sickle shape. These abnormal cells have trouble squeezing through small blood vessels, causing oxygen depletion in organs and extremities along with episodes of pain. These sickle cells also have a much shorter lifetime in the body, leaving the individual with chronic anemia.


Hemochromatosis, one of the most common genetic diseases in the United States, causes the body to absorb and store far too much iron. This excess iron is stored in organs, such as the liver, pancreas, and skin. It is due to a mutation in the gene that regulates the absorption of iron from food. If this defective gene is inherited from both parents, then the person will develop hemochromatosis. If the individual inherits the mutated gene from only one parent, the person will be a carrier but will not necessarily develop the disease.

Cystic fibrosis

Cystic fibrosis is a chronic and normally fatal disease affecting the body’s mucus glands. It targets the digestive and respiratory systems. About 55,000 individuals worldwide have cystic fibrosis. Most of these individuals are Caucasians who have ancestors who came from northern Europe. The disease appears only to those who inherit the mutated gene responsible for cystic fibrosis from both parents. Estimates are that 1 in 20 Americans carry the abnormal gene. Most of these individuals are unaware that they are carriers.


Hemophilia is a genetic disorder caused by the lack of the blood-clotting factor stemming from a defective gene on the X chromosome. Females have two X chromosomes, so if there is a defective gene on one, there is little chance that the other one is also defective. However, she will be a carrier. Males, however, have only one X chromosome, so if it is defective, then the individual will develop hemophilia. If a woman is a carrier, she has a 50 percent chance that her sons will have hemophilia and a 50 percent chance that her daughters will be carriers. Daughters of a hemophilic male will be carriers.