ADA-SCID

ADA-SCID (Adenosine Deaminase Severe Combined Immunodeficiency) is a rare genetic disorder that affects the immune system. It is one of the forms of Severe Combined Immunodeficiency (SCID), which is characterized by a severely compromised immune system, making individuals highly susceptible to infections.

Pathophysiology

ADA-SCID is caused by mutations in the ADA gene (adenosine deaminase gene) located on chromosome 20. The ADA gene is responsible for producing the enzyme adenosine deaminase, which is crucial for the breakdown of deoxyadenosine, a toxic substance to lymphocytes. In the absence of functional adenosine deaminase, deoxyadenosine accumulates, leading to the destruction of T cells and B cells, which are essential components of the immune system.

Symptoms

Individuals with ADA-SCID typically present symptoms within the first few months of life. Common symptoms include:

• Frequent and severe infections
• Failure to thrive
• Chronic diarrhea
• Skin rashes
• Hepatomegaly and splenomegaly

Diagnosis

Diagnosis of ADA-SCID is usually made through:

• Newborn screening
• Blood tests to measure ADA enzyme activity
• Genetic testing to identify mutations in the ADA gene

Treatment

Treatment options for ADA-SCID include:

• Bone marrow transplantation or hematopoietic stem cell transplantation (HSCT)
• Enzyme replacement therapy (ERT) with pegylated adenosine deaminase (PEG-ADA)
• Gene therapy, which involves inserting a functional copy of the ADA gene into the patient's cells

Prognosis

With early diagnosis and appropriate treatment, individuals with ADA-SCID can lead relatively normal lives. However, without treatment, the condition is usually fatal within the first year of life due to severe infections.

Related Pages

• Severe Combined Immunodeficiency
• T cells
• B cells
• Bone marrow transplantation
• Gene therapy