Genetic Traits Health

You may say that a certain condition or disease “runs in your family, ” but what does that really mean? Is the disease something that is truly inherited, or is it just a result of the way you and your family live, eat, and take care of yourselves? Many conditions do have very straightforward genetic factors, but most involve a complex interplay between your genes and your environment. There are four types of genetic disorders:

  • chromosomal
  • mitochondrial
  • multifactorial
  • single-gene.

Single-gene Conditions

These conditions are the result of a mutation, or change in DNA sequence, in a single gene. On their own, these genetic conditions are rare, but with 18,000 known single-gene disorders, their significance adds up. Inheritance patterns in single-gene disorders are generally straightforward:

  • Autosomal dominant: Person needs to inherit one copy of affected gene; i.e.: Huntington disease.
  • Autosomal recessive: Person must inherit two copies of mutated gene; i.e.: cystic fibrosis.
  • Codominant: Both alleles of the gene are expressed; i.e.: ABO blood group.
  • X-Linked dominant/recessive: Mutated genes on X chromosome; dominant affects females more frequently (fragile X syndrome) and recessive affects males more often (hemophilia).

Chromosomal Conditions

A genetic disorder can also appear when a chromosome, a structure made of DNA and proteins, has either too many or too few genes. A person with Down syndrome, for instance, has an extra copy of chromosome 21, for a total of 47 chromosomes instead of the usual 46.

Mitochondrial Conditions

These conditions are the result of mutations in the mitochondrial DNA. Mitochondria come from the female egg, so only mothers will pass these mutations on to their children. Blindness and hearing loss are two possible disorders that result from this type of mutation.

Multifactorial Conditions

The most common types of genetic disorders are multifactorial, meaning they are caused by the interaction of several genes with environmental factors. High blood pressure, obesity, Alzheimers disease, diabetes, and some forms of cancer are just some of the conditions that are thought to include both genetic and environmental components. Due to their complexity, multifactorial genetic disorders are hard to study and treat because researchers have yet to identify all the factors involved. To fully understand these conditions, they must know which genes are involved and which environmental triggers will cause the disease to appear.

For many of these complex conditions, scientists have identified one or more faulty genes associated with a disease, but just having these genes does not mean that you will develop it. It does mean you are predisposed, but without certain environmental factors-such as diet, lifestyle, aging, and chemical and toxin exposure-and without the buildup of other faulty genes in your body, you may not develop the condition at all. Scientists have been able to identify environmental triggers for a few genetic disorders, so avoidance and management of these can often prevent the disease in someone who is genetically predisposed.

Preventable Genetic Disorders

Once researchers determine these triggers, it is possible to decrease your risk of developing the disease, even if you have the faulty genes. For example, low folate levels in pregnant women have been linked to Spina Bifida in the developing baby. Adequate supplementation of this vitamin significantly reduces this defect; taking just 400 micrograms a day leads to a 70 percent reduction in babies born with Spina Bifida!

High dietary cholesterol is a trigger for cardiovascular disease, especially in those that are genetically susceptible. So, managing your diet can prevent this condition from developing, despite your inherited predisposition. Similarly, obesity is linked to an increased risk of developing type 2 diabetes. Exercise and proper nutrition can ward off this multifactorial disorder.

Determining Your Risk

Scientists have found genes associated with breast cancer, alcoholism, arthritis, celiac disease, and many other conditions, and they continue to research the triggers that set off these complex genetic disorders. Until they have more definite answers, take the time to sit down with a doctor to evaluate your familys medical history and look at your own lifestyle choices to see what you can do to minimize your risk. And, you can look into genetic testing to evaluate your risk for certain diseases; speak with a genetic counselor first to discuss the pros and cons of testing.

Since genetic disorders are predominantly due to genetic makeup, they can be difficult to prevent and/or treat. We have already discussed the effect that lifestyle choices can have on the development of these conditions. In addition, some medical institutions have created stem cells in order to treat up to 10 of these genetic diseases. Other scientists believe that they have developed an antibiotic that would effectively treat some of these conditions. Research is ongoing, and there is hope for those who suffer from genetic diseases, or are predisposed to them.

Resources

Dotinga, R. (2008). Genetic trait linked to alcoholism. Retrieved June 30, 2009, from the MedicineNet Web site: http://www.medicinenet.com/script/main/art.asp?articlekey=94418.

Medical News Today (2009). Antibiotics could treat Cystic Fibrosis, other genetic diseases. Retrieved July 8, 2009, from the Medical News Today Web site: http://www.medicalnewstoday.com/articles/145506.php.

The Australasian Genetics Resource Book. (2007). Environmental and genetic interactions. Retrieved June 30, 2009, from the Centre for Genetics Education Web site: http://www.genetics.com.au/pdf/factsheets/fs11.pdf.

Rose, C. (2008). Stem cells created to treat genetic disorders. Retrieved July 8, 2009, from the Top News Web site: http://www.topnews.in/usa/stem-cells-created-treat-genetic-disorders-2971.

U.S. Department of Energy Office of Science. (n.d.). Genetic disease information. Retrieved June 30, 2009, from the Human Genome Project Information Web site: http://www.ornl.gov/sci/techresources/Human_Genome/medicine/assist.shtml#disorders.

U.S. National Library of Medicine. (n.d.) Genetics. Retrieved June 30, 2009, from the Medline Plus Web site: http://www.nlm.nih.gov/medlineplus/ency/article/002048.htm.

U.S. National Library of Medicine. (n.d.). What are complex or multifactorial disorders? Retrieved June 30, 2009, from the Genetics Home Reference Web site: http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/complexdisorders.

U.S. National Library of Medicine. (n.d.). What are the different ways in which a genetic condition can be inherited? Retrieved June 30, 2009, from the Genetics Home Reference Web site: http://ghr.nlm.nih.gov/handbook/inheritance/inheritancepatterns.