What Are the 5 Most Common Genetic Disorders in the United States?
Genetic disorders are surprisingly common, affecting an estimated 1 in 70 newborns in the US. In this article, we take a look at the five most common genetic disorders and the importance of genetic carrier screening in family planning.
Thalassemia
Thalassemia is a blood disorder that affects the way the body produces hemoglobin, the protein molecule in red blood cells that is responsible for distributing oxygen throughout the body. It is more prevalent in people of Mediterranean, Middle Eastern, African, and Asian origin.
Symptoms of thalassemia include the following:
— Jaundice or pale skin
— Dark urine
— Fatigue
— Bone deformities
— Delayed development and growth
When just one parent carries the genetic disorder, he or she generally passes on thalassemia minor. However, when both parents carry the same genetic mutation, the child will usually inherit thalassemia alpha or thalassemia beta, which are more severe forms of the disorder. There is no known cure for thalassemia, but there are a variety of treatments available, including medications and supplements, blood transfusions, surgery to remove the gallbladder or spleen, and bone marrow transplants.
Tay-Sachs Disease
Tay-Sachs disease is a fatal disorder that usually presents symptoms in childhood. It causes an absence of hexosaminidase-A, a vital enzyme that prevents a lipid called GM2 ganglioside from accumulating in cells. The nerve cells of the brain are particularly affected by this genetic disorder. Tay-Sachs disease is more prevalent in those of Ashkenazi Jewish descent, with a carrier rate estimated at 1 in 27 in the US Jewish community.
Symptoms sometimes develop in the fetus in early pregnancy, though many babies born with Tay-Sachs disease do not show symptoms until they are about 6 months old, with delayed development being a common indication. By the age of 2, most children with the disorder experience severe symptoms, such as diminishing mental function and recurrent seizures. The child will gradually regress, losing mobility, sight and responsiveness. Few children with Tay-Sachs survive to the age of 5 years. There is no known cure for Tay-Sachs disease. Treatment consists of managing the disease’s symptoms.
Sickle Cell Anemia
Sickle cell anemia is a blood disorder that affects the production of hemoglobin, thus preventing red blood cells from effectively delivering oxygen to tissue and vital organs around the body. Instead of producing normal oval-shaped red blood cells, people with this genetic disorder produce characteristic sickle-shaped red blood cells. The sickle-shape hinders these red blood cells from moving around the body as they should, causing them to accumulate in blood vessels, thus impeding oxygen supply throughout the body, which can damage vital organs such as the liver, lungs, spleen, kidneys, and brain. A secondary complication of sickle cell anemia is pulmonary hypertension (high blood pressure in the vessels supplying the lungs), which can result in heart failure in severe cases.
Sickle cell anemia is more prevalent in people of African, Middle Eastern, Indian, and Mediterranean origin, affecting an estimated 1 in 500 African Americans. To help patients manage the symptoms of the disease, doctors prescribe pain medications, blood transfusions, and bone marrow transplants.
Recent clinical trials involving gene therapy look promising. In fact, this treatment appears to have cured one adolescent boy, thereby offering hope to millions of people around the world living with sickle cell.
Cystic Fibrosis
Cystic fibrosis is the most common, fatal, inherited disease in the US, affecting around 1 in 2,500 Caucasian newborns. Symptoms include an overproduction of a thick, sticky mucus that builds up in the lungs and other vital organs in the body. This mucus can clog a person’s airways and lead to infection. Over time, cystic fibrosis causes permanent damage to the lungs in the form of cysts and scar tissue.
The disease was once considered a fatal childhood illness, but improved treatments have extended life expectancy of people with cystic fibrosis. Today, people with the disorder can live well into adulthood.
Both parents must carry the genetic mutation associated with cystic fibrosis in order to pass the disease on to their children. Though the symptoms are treatable, there is no known cure for cystic fibrosis.
The Rise of Pre-Conception Genetic Carrier Screening
Today, many couples opt for preconception carrier screening, allowing medical practitioners unparalleled insight into their genetic makeup to determine their risk of passing a genetic mutation on to their child. Even in the rare scenario in which both parents carry the same genetic mutation, medical interventions can help prospective parents to have their own children while minimizing the risk of passing on the disorder. By adopting this proactive approach, parents and specialists can make informed choices to achieve the best possible outcome.
