Adenosine Deaminase Deficiency

Adenosine deaminase deficiency (ADA 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 ADA deficiency are unable to fight off most types of infections, including bacterial, viral and fungal infections. Most people with ADA deficiency develop symptoms before 6 months of age. The earliest symptoms of ADA deficiency include pneumonia, chronic diarrhea, widespread skin rashes, slowed growth, and/or developmental delay. Some people with ADA deficiency will develop symptoms later in life. The symptoms in the late-onset form are typically milder than in the form that occurs in infancy. ADA deficiency is caused by mutations 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.  Currently, the most effective treatment is transplantation of blood-forming stem cells from the bone marrow of a healthy brother or sister of the person with ADA deficiency.