Family History Initiative
Related Terms
Autosome, cancer, chromosome, DNA, disease, dominant, gene, inheritance, inherited genetic disease, My Family Health Portrait, nucleus, recessive, sex chromosome, X-linked recessive.
Background
The Family History Initiative is a project to help individuals track genetic diseases in their families. Many different human diseases are a result of a mutation or error in a gene. Genes are sequences of deoxyribonucleic acid (DNA) that contain instructions for making proteins. Mutations in a gene may lead to defective or reduced levels of specific proteins, which may in turn lead to a disease. Proteins are important because they carry out many functions in the body.
Genes are passed down from generation to generation in a family. Healthy individuals have two copies of most genes. One copy is inherited from the mother, and one from the father. Mutations, or errors, in genes may lead to an individual developing a genetic disease. To inherit the trait for an autosomal recessive disease such as Duchenne muscular dystrophy, both copies of a specific gene must be defective in order for the disease to appear. To inherit the trait for an autosomal dominant disease, such as polycystic kidney disease, only one copy of the gene must be defective for the disease to appear.
Genes are located in a compartment of the cell called the nucleus and are contained in structures in the nucleus called chromosomes. Chromosomes are made up of DNA and proteins, and each chromosome contains hundreds of genes. Humans have 46 chromosomes in each cell (22 pairs of autosomes and one pair of sex chromosomes). Humans receive one copy of each autosome from each parent. Additionally, humans have two sex chromosomes in each cell. Females have two X chromosomes and males have one X chromosome (inherited from the mother) and one Y (inherited from the father).
Some genetic diseases are inherited in an X-linked pattern, meaning that the genetic mutation causing the disease is located on the X chromosome. Some genetic diseases are caused by mutations on autosomes.
Tracking genetic diseases may help individuals understand their risk of developing a disease. The family history initiative uses a computer interface to allow individuals to input information about different diseases members of their family have had. This information is organized into a family tree that shows which family members are affected with a specific disease.
Based on the inheritance pattern of the particular disease, individuals can determine the probability that they (or other family members) have inherited a mutated gene and re therefore at risk for developing the disease. However, the causative mutations are not yet known for all types of genetic diseases. In cases in which an inheritance pattern or causative mutation is not yet known, the specific risk to family members may not be clear from the family tree.
By identifying who may be at risk for developing a disease, doctors may be able to perform genetic screening to check for disease-causing mutations in high-risk individuals. Early detection of disease-causing gene mutations may allow individuals access to treatments that may reduce the severity of symptoms or delay the onset of disease.
Methods
To participate in the family history initiative, an individual must first download a computer program called My Family Health Portrait. This program is available as a free download from the U.S. Department of Health and Human Services.
After installing the program, individuals should follow the program instructions and input the requested information. Users are asked to input personal information, such as name, height, and weight. They are then asked to list all of their blood relatives (e.g., cousins and uncles).
Next, users indicate for themselves and for each family member whether any diseases have been diagnosed. My Family Health Portrait automatically tracks six different diseases: heart disease, stroke, diabetes, breast cancer, ovarian cancer, and colon cancer. However, users may add any additional diseases that may have been present in their family and that they want to track.
After the information has been entered, the program can generate a graphical family tree, which allows users to see which individuals in their family are affected with a disease and how those individuals are related. Assuming that an individual has entered correct information into the program, this family tree should provide accurate information.
Individuals may then print this information and discuss it with their doctor, particularly focusing on those diseases that are inherited and what the individual's risk is for developing that disease.
Research
Not applicable.
Implications
Doctors may be able to determine whether an individual is at an increased risk for developing a disease based on the information supplied as part of the family history initiative. Based on the inheritance pattern of a particular disease, individuals may be able to determine the probability that they have inherited a mutated gene and are at risk for developing the disease. For example, breast cancer may not be apparent early in life, but an individual may learn that she is at increased risk of developing it by using the family history initiative.
In many cases, genetic mutations have been linked to specific diseases. Therefore, a doctor determines an individual's risk for a disease based on family history, and may order genetic testing to look for mutations in genes. This testing may allow doctors to more accurately diagnose a disease or establish whether an individual is at risk for developing a disease. Most genetic tests are not done routinely, but rather when a specific disease is suspected.
Early identification of individuals at risk for certain diseases, before symptoms are present, may allow individuals to make lifestyle adjustments or to start certain treatments that may delay the onset of the disease or reduce the severity of symptoms once they develop. For example, individuals at risk of developing heart disease could start consuming a low-fat, low-cholesterol diet and begin a regular exercise program.
Parents may be able to use information from the family history initiative to determine what risk they have of passing on certain genetic diseases to their children. By identifying which diseases run in their family and checking to see if they carry any of the disease-causing genetic mutations, parents may make informed decisions for family planning. Genetic counselors may be able to help parents understand these risks and the implications of test results.
Limitations
Based on the inheritance pattern of a particular disease, the family history initiative may help individuals determine the probability that they or other family members have inherited a mutated gene and are at risk for developing the disease. However, the causative mutations are not yet known for all types of genetic diseases. In cases in which an inheritance pattern or causative mutation is not yet known, disease risk may not be apparent from the family tree.
In some diseases, genetic mutations place individuals at risk for developing a disease. However, not all individuals with the genetic mutation actually develop the disease. Therefore, while the family history initiative may be able to identify individuals who are at risk of developing a disease, it may not be able to provide a definitive diagnosis or be used to determine conclusively who will develop the disease. In addition, some genetic diseases may not be preventable. Therefore, even though an individual knows he or she is at increased risk for developing a disease, he or she may not be able to take any action to prevent it.
Future research
Not applicable.
Author information
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
Bibliography
Carmona RH, Wattendorf DJ. Personalizing prevention: the U.S. Surgeon General's Family History Initiative. Am Fam Physician. 2005 Jan 1;71(1):36, 39.
Department of Health and Human Services. .
My Family Health Portrait Home Page. .
National Human Genome Research Institute. .
Natural Standard: The Authority on Integrative Medicine. .
Wolpert CM, Speer MC. Harnessing the power of the pedigree. J Midwifery Womens Health. 2005 May-Jun;50(3):189-96.