Top Ten Worst Genetic Diseases

Inherited genetic diseases affect millions worldwide. Family health history is the biggest predictor of genetic disease. Research is ongoing to detect and treat genetic disease. The decision to be tested for genetic disease is often difficult and includes many moral and ethical issues. Genetic makeup passed on from parents and grandparents affects a person's life and the life of their own children. The worst genetic diseases are incurable.

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Cystic Fibrosis

Cystic fibrosis is the most common, fatal genetic disease, affecting about 30,000 people in the United States, according to the National Human Genome Research Institute. Cystic fibrosis causes the body to produce thick, sticky mucus that clogs the lungs, leads to infection and affects the pancreas. Breathing is difficult, and digestive enzymes are blocked, which inhibit the absorption of food nutrients.


Tay-Sachs causes death at any early age, usually around five years old, because of a missing enzyme called Hex-A. Tay-Sachs causes progressive destruction of the nervous system and brain. There is no treatment, only management of the symptoms.


Considered a disease, addiction to alcohol is most likely passed down through genetic makeup. If one or both parents are addicted to alcohol, then the children of those parents appear to have a higher chance of being addicted to alcohol. As of 2010, no specific genes have been identified as the cause of alcoholism.

Breast and Colon Cancer

One in nine women has a chance to develop breast cancer. The BRCA1 and BRCA2 inherited genes predispose a woman to a greater chance of breast or ovarian cancer, but not all breast cancers are due to genetic reasons. A family history of colon cancer means there is a reason to believe it may be genetic. As with other cancers, genetic reasons may not be the only reasons for developing cancer.

Sickle Cell Disease

Having the single expression of the gene for sickle cell does not cause the disease. The gene evolved to protect people from malaria. However, getting the gene from both parents, a double dose causes the red blood cells to “sickle” spontaneously during a stress crisis. The sickled cells get stuck in small capillaries and destroy joints and organs. Eventually, the victim will die of organ failure.


Obesity is fast becoming the number one inherited disease in the United States. It is a complicated disease occurring from genetic and environmental stimuli. The children of obese parents have a much greater than average risk of being obese. No definitive research has yet discovered the specific genetic makeup involved, yet it does appear to have elements of both inherited genetic tendencies and the dietary habits of the parents.

Heart Disease

Many types of heart disease are passed on genetically. One in particular, called Brugada disease, is treatable as a genetic disease. If someone in the family has Brugada, a specific abnormal heart rhythm, the chances are good for other members to carry the gene and all siblings should get an electrocardiogram test. The Brugada EKG pattern is recognizable and diagnostic. A pacemaker is implanted to correct the abnormal heartbeat.


Hemophilia, a bleeding disorder caused by the absence of genetic clotting factors, is inherited from one or both parents. Replacing the missing factors is the way to manage the various bleeding disorders. Specific tests are available to determine which clotting factors are missing.

Huntington’s Disease

A famous disorder affecting the likes of Woody Guthrie and others, this genetic disease slowly kills victims by affecting cognitive function and neurological status. The National Human Genome Research Institute says that in the United States alone, about 30,000 people have Huntington’s. In addition, 35,000 people exhibit some symptoms and 75,000 people carry the abnormal gene.


Hereditary hemachromatosis affects the body’s ability to regulate iron absorption. Severe organ damage can result from lack of treatment. Removing the iron rich blood is the quickest and safest method of treating this disease.