How to read your medical test report: Genetic testing

Here's how to read your genetic testing report.

A gene, made of DNA and RNA, is the basic unit of heredity. It contains information that is passed on to the offspring. Our genes decide everything about us - our eye and skin color, height, blood type, behavioral traits, susceptibility to diseases, etc.

Genetic tests what are they?

Genetic tests are medical tests that study your DNA or genes to identify changes in them. They are performed on a sample of blood, skin, hair, or other tissue. Amniotic fluid (the fluid surrounding the baby in the womb) may be used for prenatal genetic testing. A sample of cells from the inner side of the cheek may also be used. There are numerous genetic tests available which use different methods for genetic testing. A gene test (DNA Testing) studies a specific gene or it s DNA when a specific genetic mutation is suspected. Chromosome testing or karyotyping is a more general test which analyzes whole chromosomes. Biochemical genetic tests study abnormalities of enzymes or proteins.

When are the tests recommended?

Genetic tests are recommended to identify or rule out genetic or chromosomal abnormalities. A gene test is advised when a specific genetic mutation is suspected to be responsible for your signs and symptoms. It can help diagnose hemophilia, cystic fibrosis (build-up of sticky mucus in the lungs), sickle cell anemia and polycystic kidney disease (cysts inside the kidneys). Chromosome testing is advised if the signs and symptoms of a condition are suspected to be gene-related but the specific gene involved is not known. The test is often used to test children with physical or developmental problems without any obvious cause and for couples experiencing repeated miscarriages.

Genetic screening is used in people who have no obvious symptoms but may be at a risk of developing a disease. The testing enables them to make informed decisions about the course of action they wish to take. Angelina Jolie learnt from that she carried a mutation of the BRCA1 gene and underwent a preventive double mastectomy. The genetic tests can help screen people with a family history of genetic disorder. They can also examine a couple to assess their chances of having a child with a genetic condition. Antenatal screening is carried out during pregnancy to check for common genetic conditions, such as Down s syndrome, sickle cell anemia and thalassemia and in people at risk of developing a genetic condition like Huntington s disease (a disorder of brain nerve cells degeneration). Screening just after birth may be advised in susceptible children to identify and treat their genetic disorders. Genetics could help assess your diabetes risk too.

Pre-implantation genetic diagnosis (PGD) is a procedure used in assisted reproductive techniques to prevent the passing of certain disorders from parents to the child. The test, done prior to implantation, detects genetic changes in embryos created during in-vitro fertilization. Forensic genetic testing is used for legal purposes. It can help identify disaster or crime victims, and as well link a suspect to the crime scene. The test is also used to establish biological relationships between people.

Reading your genetic test report

The genetic tests results are not always forthright. They may need interpretation. A test may confirm or rule out a suspected genetic disease. It may predict your chances of developing a genetic condition. It can indicate whether you are a carrier of a particular genetic mutation.

Test result:

Positive - a change in a gene, protein or chromosome observed

Negative -no change in a gene, protein or chromosome observed

Inconclusive - change in DNA found, but it could be a natural variation and not associated with any disorder

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