What Genetic Diseases Can I Get Tested for?

Genetic carrier screening is carried out worldwide to detect mutated genes and diagnose rare genetic disorders. Here we take a look at some of the most common diseases for which people are tested and the risks associated with carrying faulty genes.

Genetic Carrier Screening in Pregnancy

Carrier screening is performed as a matter of course in many countries during pregnancy to determine whether a parent carries a genetic mutation that could pose a risk to the baby. The odds are that as a carrier, the parent shows no symptoms of the condition and therefore is unaware of his or her carrier status. This can lead to serious genetic disorders passing undetected to subsequent generations.

Ideally, prospective parents are screened prior to trying to conceive, so that the risk can be assessed ahead of time. Many genetic disorders require two faulty gene copies in order to develop — i.e., one faulty gene from the mother and one from the father. The mother is generally tested first. If no faulty genes are identified, screening often ends there.

In a recent study, 24 percent of patients tested were found to be carriers for at least one genetic mutation. Having said that, many genetic conditions are rare, with up to 100 genetic disorders for which patients can be tested. Here we take a look at some of the most serious.

Cystic Fibrosis

Cystic fibrosis is the most common genetic condition. It is most prevalent in Caucasians. Cystic fibrosis occurs in around 1/3,000 white newborns in the US. It is less prevalent in African Americans affecting around 1/17,000, with Asian Americans facing the least risk at around 1/31,000.

The disease is characterized by the presence of a thick, sticky mucus that can build up and damage many of the body’s organs. It is particularly damaging to the digestive and respiratory systems. Symptoms can range in severity amongst affected individuals. Complications can include infections and permanent lung damage caused by cysts and scar tissue.

While cystic fibrosis used to be considered fatal in childhood, improved treatments and better disease management systems mean that many people with the condition now live well into adulthood.

Sickle Cell Disease

The following demographics are considered to be at high risk for sickle cell disease: African, Caribbean, Central or South American, Mediterranean, Middle Eastern, and Indian. Research by the National Institute of Health shows that 1 in 13 African-Americans are carriers of the gene.

Sickle cell disease, or sickle cell anemia as it is also known, causes abnormalities in red blood cells that prevent them from traveling around the body and delivering oxygen as they should. Instead, they get lodged in blood vessels, causing pain, damaging organs, and increasing the risk of infection.

There is no cure for sickle cell disease, though medication can alleviate pain and reduce the risk of infection.

Thalassemia

Thalassemia covers a spectrum of blood disorders, with symptoms ranging from relatively mild to severe anemia and other serious complications. Over 2 million people in the US are believe to carry the gene responsible. It is more prevalent in the following populations: Southeast Asian, Indian, Chinese, African, Middle Eastern, and Mediterranean.

A common symptom of the condition is a mild form of anemia. When one partner is found to be a carrier of thalassemia and another a carrier of sickle cell disease, the baby is considered to be at high risk for thalassemia.

Tay-Sachs Disease

Tay-Sachs disease is a fatal disorder affecting the central nervous system. Approximately 1/250 people in the US are carriers. Amongst Irish Americans, that figure rises to 1/50. The disease is also prevalent in central and eastern European Jews, Cajuns, and French Canadians, with a carrier rate of around 1/27.

Tay-Sachs disease is caused by the absence of a crucial enzyme called Hex-A. Without Hex-A, a fatty substance accumulates abnormally in cells, particularly the nerve cells of the brain, causing progressive damage.

The Future of Prenatal Screening

When parents are found to be carriers of a specific disorder during pregnancy, the next step is often to test the fetus. This has historically carried a certain degree of risk, with the somewhat invasive procedure of removing amniotic fluid or a sample from the placenta occasionally causing miscarriage.

A new, non-invasive procedure has been developed that can provide information about the fetus via a blood sample from the mother. Blood taken in the first or second trimester of pregnancy can reveal DNA information from the fetus.

Pre-Pregnancy Genetic Screening

Pre-pregnancy screening is becoming increasingly popular. The prospective mother is usually tested first. If she tests negative, the process generally ends there. If she does test positive, the next step would be to test her partner. Even in a worst-case scenario in which both parents test positive for the same disorder, there is still a 75 percent chance that a potential child will be born healthy. Additionally, IVF innovations in recent years mean that through pre-implantation screening, that 25 percent risk can be virtually eliminated.

Genetic screening has revolutionized medicine. It is hoped that one day, this relatively modern innovation will be used to eliminate many debilitating conditions completely.