Lineages

Obtaining an accurate family medical history is a great tool to help identify disease risk and develop a personalized prevention program. An individuals genetic history can be studied to determine if there are any potentially inherited conditions present in parent and child.

We inherit our genes from both our parents. If a parent or other family member has a genetic risk for a disease, a child may inherit that risk as well. Surrogate mothers who are a child’s genetic mother can also pass along their genetic predispositions.

Genetic markers for many conditions have been discovered by comparing the DNA of healthy and diseased people. Here are just a few of the many conditions with associated genetic markers:

  • Alzheimer’s disease
  • breast cancer
  • diabetes
  • Down syndrome
  • Huntington’s disease
  • sickle cell anemia.

This information is now accessible to the general public. A disease risk profile is relatively inexpensive and usually only requires a swab of saliva.

Disease Risk Profiling

Genetic testing for risk of inherited diseases has many potential benefits. Since many of the conditions profiled have both genetic and environmental causes, people found to be at risk can make lifestyle changes to prevent or delay getting sick. A high risk result also encourages medical screenings for early detection and treatment.

Genetic profiling can be lifesaving for people with a family history of diseases such as breast cancer. Women who find they have breast cancer genes can increase their chances of detecting the cancer early with education, self tests and frequent mammograms. They can also adopt healthy life changes to reduce cancer risk. If they do develop cancer, they are often able to get medical attention before it becomes life threatening.

Genetic Counseling

Genetic counseling is extremely important when having genetic testing. This counseling helps people understand their test results and deal with the many emotional reactions that may be experienced. Genetic counseling can also help with family planning for those with a family history of inherited conditions. Here are a few basics to help you understand the results of a genetic testing:

  • If you test positive for a disease risk, it does not mean you will definitely get the disease. It just means you have a higher risk than the general population.
  • While a negative test result for disease risk is good news, it does not guarantee that you will not get the disease. It just means you have the same risk as the general population.
  • If you are found to carry the genes for an inherited disease, your genetic counselor will help you determine the risk of passing the condition on to your children. Often both parents have to carry a gene for a child to be affected.

Maternal and Paternal Lineages

Everyone has both a maternal and paternal genetic history. Maternal lineages involve the history of mothers and daughters, while paternal lineages are a history of fathers and sons. DNA from certain maternal and paternal cells is only passed from mothers to children or fathers to sons:

  • Mitochondrial DNA is only inherited from ones mother. Both boys and girls inherit their mother’s mtDNA.
  • Y-Chromosome DNA, also known as yDNA, is only inherited from ones father and passed only to sons.

Both of these types of DNA are normally used for answering questions of genealogy. Paternity can be determined from yDNA as well. No vital genes are located on yDNA, but some diseases are linked to it. Mutations in mitochondrial DNA result in diseases such as exercise intolerance and Kearns-Sayre syndrome (KSS).

Genetic Imprinting

Gene function can change without any changes in DNA sequence. Referred to as epigenetics, this view explains the difference in individuals that are often described as nature versus nurture. Every cell in the body has the same genetic material. Which genes are turned on or off to produce certain proteins is determined by each cell type. Epigenetic regulation allows each cell type to exercise control over its development and activate only certain genes.

The view that maternal and paternal genes are in a power struggle to become dominant in offspring is now being challenged by some researchers. The theory of genetic cooperation suggests that genetic imprinting is at play. This idea states that only one of the two sets of genes are being used and the second is silenced, unlike Mendelian genetics.

Reducing your Risk of Inherited Disease

Some healthy lifestyle changes to reduce the risk of many inherited diseases include:

  • adequate exercise
  • eating a healthy diet, low in animal fats and sugar and high in fresh fruits, vegetables and whole grains
  • maintaining an appropriate weight for your height
  • reducing stress.

Resources

University of Manchester (2006). Parental Genes do Whats Best for Baby. Retrieved November 22, 2008, from the PhysOrg.com Website: http://pda.physorg.com/lofi-news-offspring-genes-imprinting_84027061.html.

TS-Si News Service (2007). How Does Maternal and Paternal DNA Combine to Create Unique Offspring?. Retrieved November 22, 2008, from the TS-Si News Service Web site: http://www.ts-si.org/biological-sciences/2614-how-does-maternal-a-paternal-dna-combine-to-create-unique-offspring.html.