Genetic tests determine whether you, your partner or your baby carry genes for inherited disorders. The type of genetic test needed to make a specific diagnosis depends on the particular illness that a doctor suspects.

Two types of genetic testing techniques are used.

Predictive genetic testing

Predictive genetic testing is used to:

    • Detect mutations associated with disorders that appear after birth, often later in life
    • Identify mutations that could increase your risk of developing disorders based on your genetic makeup, such as certain types of cancer.

Preventive genetic testing

    • Preventative genetic testing is used to identify certain gene mutations (single nucleotide polymorphism or SNPs) that are expressed in an unfavourable lifestyle environment
    • SNP intervention is used to successfully treat gene mutation with lifestyle changes, proper nutrition, and vitamin and mineral supplementation
    • Modern genomics is based on personalised prevention. Although usually used to stop the development of age-related degenerative diseases, prevention is recommended for both young and old.

Many different types of body fluids and tissues are used in genetic testing. For deoxyribonucleic acid (DNA) screening, only a tiny bit of blood, skin, bone or other tissue is needed.

Genes and chromosomes

We all have a unique set of chemical blueprints in our DNA that affects how our body looks and functions. DNA carries the codes for genetic information and is made of linked subunits (nucleotides). Each nucleotide contains a phosphate molecule, a sugar molecule (deoxyribose) and one of four “coding” molecules called bases (adenine, guanine, cytosine or thymidine). The sequence of these four bases determines each genetic code.

The segments of DNA that contain the instructions for making specific body proteins are called genes. Scientists believe that human DNA carries about 25 000 protein-coding genes. Each gene may be seen as a “recipe” in a cookbook.

Genetic problems

Errors to the genetic code or “gene recipe” can happen in a variety of ways. Sometimes information is missing from the code, other times codes have too much information or have information that is in the wrong order.

These errors can be big (e.g. if many or all ingredients are missing in a recipe) or small (if just one ingredient is missing). Whether the error is big or small, it can cause you to have a disability or be at risk of a shortened life span.

Abnormal numbers of chromosomes

When a mistake occurs during cell division, it can cause an error in the number of chromosomes a person has. The developing embryo then grows from cells that have either too many chromosomes or not enough.

Genetic testing enables those who are at risk to be carefully monitored by their doctors and thereby increase their odds of survival.

 

Sources
Nina Powell-Hamilton, MD (April 2013)
www.8thsense.co.za
www.genediagnostics.co.za