Genetic Testing Health

How many times have you seen someone look at a newborn baby and coo, “Oh, he has his mother’s eyes?” Or heard a musician brag that she gets her artistic streak from her father’s side of the family?

We know that we inherit certain traits from our parents, thanks to the passing along of DNA in the genetic code. Unfortunately, we also inherit genetic disorders, which can cause a multitude of health problems.

Every human being inherits 46 chromosomes – 23 from each parent. Of these, 44 chromosomes are identical, and the last two determine the person’s gender. Females have two X chromosomes; males receive an X chromosome from their mother and a Y chromosome from their father.

Each chromosome contains thousands of genes, each of which contains millions of base pairs of DNA. The sequence of DNA dictates a person’s hair color, skin tone, height and thousands of other individual characteristics.

Any change in the sequence of bases is called a genetic mutation. These mutations can cause the body’s proteins to stop functioning normally, which can lead to disease.

Common Hereditary Diseases

A strong link exists between health or illness and genetics. Some diseases, such as certain types of cancer, are caused by a genetic mutation in a cell or a group of cells. Most genetic diseases, however, are caused by a combination of small variations in genes and outside factors.

Many of the diseases caused by genetic mutations, such as breast cancer or colon cancer, also have hereditary forms. This means that the genetic variants run in the family and can strongly raise each family member’s chance of contracting the disease.

Research on the genetics of mental health has shown that many mental illnesses may be hereditary, including schizophrenia, manic depression, early onset depression, autism and ADHD.

Genetic diseases typically fall into three categories:

  • Chromosome disorders. These genetic diseases are caused by errors on any of the 23 pairs of chromosomes in the body. There may be broken or missing pieces, or too many pieces or copies. The most well-known chromosome disorder is Down syndrome, which is caused by an extra copy of chromosome 21.

  • Multifactoral inheritance disorders. Heart disease and most types of cancer are common genetic diseases in this category. These disorders are caused by a combination of small deviations in genes, coupled with environmental factors. Some scientists believe that a genetic link exists for disorders such as alcoholism, obesity, mental illness and dementia.

  • Single gene disorders. These disorders are caused by a mutation in a single gene, which may occur on one or both chromosomes. Examples of single gene disorders include sickle cell anemia, cystic fibrosis and Tay-Sachs disease.

Down Syndrome - Genetics and Down Syndrome

Genetic Testing

Testing for genetic disorders may be helpful for high risk individuals. For example, a couple with a family history of inherited diseases may choose to be tested before they consider having a baby. Or someone with a family history of common diseases such as cancer or Parkinson’s disease may assess their own risk of contracting these illnesses.

The types of genetic testing available today include:

  • Carrier testing, which reveals whether a person is a carrier of certain genetic mutations. Carriers may display no symptoms themselves, but they are capable of passing the mutation along to their children.
  • Diagnostic testing helps manage or treat an existing disorder by identifying the genetic condition that is causing the illness.
  • Newborn screening is used to test babies shortly after they are born to find out whether they have any diseases that could lead to problems with health and development.

  • Prenatal testing helps to determine whether a fetus has certain diseases.

Resources

Adams, A. (2000). Genetics 101: Overview of genetics. Retrieved August 28, 2008, from the GeneticHealth Web site: http://www.genetichealth.com/G101_Genetics_Demystified.shtml.

Gans, S. (2005). Gene hunting. Retrieved August 28, 2008, from the About.com Web site: http://bipolar.about.com/cs/genetics/a/nihmhuntgene.htm.

Genome.gov. (n.d.). Frequently asked questions about genetic disorders. Retrieved August 28, 2008, from the National Human Genome Research Institute’s Web page: http://www.genome.gov/19016930.

Halsey Lea, D. (2008). Genetic testing: How it is used for healthcare. Retrieved August 28, 2008, from the National Institutes of Health Web site: http://www.nih.gov/about/researchresultsforthepublic/genetictesting.pdf.

Iannelli, V. (2005). Down syndrome facts. Retrieved August 28, 2008, from the About.com Web site: http://pediatrics.about.com/od/downsyndrome/a/05_facts_down_s.htm.

Understanding Genetics. (n.d.). Genetics and health. Retrieved August 28, 2008, from the Tech Web site: http://www.thetech.org/genetics/feature.php.