Adenosine Deaminase (ADA) is an enzyme that plays a crucial role in the metabolism of purines, which are essential components of DNA and RNA. It catalyzes the deamination of adenosine, converting it into inosine. This process is vital for maintaining the balance of nucleotides in the body and is particularly important in the immune system. Deficiency in Adenosine Deaminase can lead to severe combined immunodeficiency (SCID), a condition that severely weakens the immune system, making individuals highly susceptible to infections. ADA is also a target for certain therapies, including gene therapy, to treat SCID and other related disorders.