Severe combined immunodef due to adenosine deaminase defic

This code identifies a rare, inherited primary immunodeficiency characterized by a severe defect in both T-cell and B-cell immunity, resulting from a deficiency in the enzyme adenosine deaminase (ADA). Patients present with recurrent, severe infections, failure to thrive, and often have skeletal abnormalities and neurological issues. Without treatment, it is typically fatal in infancy.

Assign this code for patients diagnosed with severe combined immunodeficiency (SCID) specifically attributed to adenosine deaminase deficiency. Documentation should clearly state the diagnosis of ADA-SCID, often supported by genetic testing confirming ADA gene mutations and enzyme activity assays. This code is appropriate for initial diagnosis and ongoing management of this specific genetic disorder.

• Differentiate from other forms of SCID; ensure documentation explicitly states "adenosine deaminase deficiency."
• Consider sequencing this code as the primary diagnosis when it is the reason for the encounter, especially for diagnostic workup or treatment initiation.
• Do not confuse with other primary immunodeficiencies that do not involve ADA deficiency.