> Genetic Disease

• Symptoms & Characteristics
• Treatment
• How Common Is It?
• Genetics & Inheritance
• Genetic Testing
• Support & More Information
• Alternative Names

Last Reviewed June 2, 2009

Symptoms & Characteristics

A genetic condition (also called genetic disease or disorder) is caused in whole or in part by an alteration (mutation) in a gene or by a different form (variation) of a gene.

In the past, genetic research has focused on rare diseases that are caused by a mutation in one gene or a group of genes. These mutations can either be inherited or occur sporadically.

We are now learning that almost all diseases have a genetic component. Researchers are beginning to understand how small genetic variations that we all possess contribute to common disease risk. Much research is now focused on identifying these genetic variations, determining their effects on disease risk, and understanding the mechanisms in which they interact with each other as well as non-genetic factors. Hopefully, one day, we will be able to use this knowledge to better detect, prevent, and treat disease.

Treatment

The overall treatment, prognosis and management of a genetic condition is specific to the disease and it's symptoms.

How Common Is It?

Over 4,000 genetic conditions have been documented.

Genetics & Inheritance

There are three main categories of genetic conditions:

• Single gene disorders are caused by mutations in a single gene. The mutation may be present in one or both copies of the gene (one gene copy is inherited from each parent). Single gene disorders usually have a clear pattern of genetic inheritance. Some examples of common single gene disorders are cystic fibrosis, sickle cell anemia, Fragile X syndrome, Huntington's disease, Hemophilia A and Tay-Sachs disease.

• Chromosome abnormalities are caused by an excess (gain) or deficiency (loss) of genetic material on chromosomes or by structural changes within the chromosomes themselves. The most common chromosome abnormality, Down syndrome, is caused by an extra copy of chromosome 21; however, no single gene on chromosome 21 is abnormal. Chromosome abnormalities, such as Down syndrome, are usually not inherited but occur sporadically.

• Multifactorial conditions (also called complex diseases) are caused by a combination of genetic variations, environmental factors and lifestyle factors. Although multfactorial conditions can "run in families," they typically do not have a clear pattern of genetic inheritance. This can make it difficult to assess the likelihood of a person inheriting or passing down the condition.

Genetic Testing

Clinical genetic testing is not available for every known genetic condition. The availability of clinical genetic testing for a specific condition can be discussed with a genetic professional.

Informational genetic testing for some multifactorial conditions is available online (over the internet). At this point, many genetic professionals do not consider this testing clinically useful or medically relevant, but for informational purposes only.

It is always recommended to see genetic counseling with a trained genetic professional for a complete evaluation, accurate diagnosis, and discussion of the benefits and limitations of testing and recurrence risk. Use our find a genetic professional directory to locate a trained genetic professional in your area.

• A medical geneticist can also be found at the American College of Medical Genetics website.

• A genetic counselor can also be found at the National Society of Genetic Counselors website.

Support & More Information

More information and support can be found at:

• MedlinePlus

Alternative Names

• genetic disease
• genetic disorder