About Severe Combined Immunodeficiency Due to Adenosine Deaminase Deficiency
The New York Center for Rare Diseases supports the mission and guidelines of the Genetic and Rare Diseases Information Center (GARD). The following information is provided by the NIH.
Summary
Severe combined immunodeficiency due to adenosine deaminase deficiency is an inherited condition that damages the immune system and is a common cause of severe combined immunodeficiency (SCID). People with SCID due to adenosine deaminase deficiency are unable to fight off most types of infections, including bacterial, viral and fungal infections. Most people with severe combined immunodeficiency due to adenosine deaminase deficiency develop symptoms before 6 months of age. The earliest symptoms of severe combined immunodeficiency due to adenosine deaminase deficiency may include pneumonia, chronic diarrhea, widespread skin rashes, slowed growth, and/or developmental delay. Some people with ADA deficiency may develop symptoms later in life. Severe combined immunodeficiency due to adenosine deaminase deficiency is caused by genetic changes in the ADA gene and is inherited in an autosomal recessive manner. Diagnosis may be suspected by newborn screening or symptoms and confirmed by blood and genetic test results.
Causes
What Causes This Disease?
Genetic Mutations: Severe combined immunodeficiency due to adenosine deaminase deficiency is caused by genetic mutations, also known as pathogenic variants. Genetic mutations can be hereditary, when parents pass them down to their children, or they may occur randomly when cells are dividing. Genetic mutations may also result from contracted viruses, environmental factors, such as UV radiation from sunlight exposure, or a combination of any of these.
If you suspect you may have this disease, you may want to start collecting your family health history. Information such as other family members who have had similar symptoms, when their/your symptoms first appeared, or exposures to any potential disease-causing environmental factors should be discussed with your medical team.
Known Genetic Mutations: Severe combined immunodeficiency due to adenosine deaminase deficiency is caused by genetic mutations in the following known gene(s):
ADA
Given these known genetic mutation(s), you may want to ask your health care team if genetic testing is right for you. Genetic tests are laboratory tests that use samples of blood, saliva, or other tissues to help identify changes in genes, chromosomes, or proteins. Genetic testing can help confirm or rule out a suspected genetic disease, or can provide other useful information to your health care team.
Disruption in Metabolism: Severe combined immunodeficiency due to adenosine deaminase deficiency is caused by a disruption in a person’s metabolism. Metabolism is the series of chemical reactions in our body that turns the food we eat into energy and removes toxins. Hormones and specific proteins, called enzymes, help make the right chemical reactions happen in the right order. However, genetic changes can prevent hormones or enzymes from working properly, which can lead to a disruption in metabolism such as energy not being created for the body or toxins not being removed from the body.
Can This Disease Be Passed Down From Parent to Child?
Yes. It is possible for a biological parent to pass down genetic mutations that cause or increase the chances of getting this disease to their child. This is known as inheritance. Knowing whether other family members have previously had this disease, also known as family health history, can be very important information for your medical team.
There are multiple ways, or patterns, a disease can be inherited depending on the gene(s) involved. Based on GARD’s current data, this disease can be inherited in the following pattern(s):
Autosomal Recessive: Autosomal means the gene involved is located on one of the numbered chromosomes. Recessive means that a child must inherit two copies of the mutated gene, one from each biological parent, to be affected by the disease. A carrier is a person who only has one copy of the genetic mutation. A carrier usually doesn’t show any symptoms of the disease.
If both biological parents are carriers, there is a 25% chance their child inherits both copies of the mutated gene and is affected by the disease. Additionally, there is a 50% chance their child inherits only one copy of the mutated gene and is a carrier.