Other adenosine deaminase deficiency

This code signifies a rare genetic disorder characterized by a partial or atypical deficiency of the enzyme adenosine deaminase (ADA), leading to an accumulation of toxic metabolites that impair immune cell function. It results in a spectrum of immunodeficiency, often less severe than complete ADA deficiency, but still predisposing individuals to recurrent infections and other immune dysregulation.

Use this code when documentation specifies an adenosine deaminase deficiency that does not fit the criteria for severe combined immunodeficiency (SCID) due to complete ADA deficiency. This applies to patients with residual ADA enzyme activity or atypical clinical presentations of ADA deficiency. Supporting documentation would include genetic testing results confirming an ADA gene mutation, enzyme assays showing partial ADA deficiency, and clinical findings consistent with a milder or variant immunodeficiency.

• Differentiate from D81.30 (Adenosine deaminase deficiency, unspecified) and D81.31 (Severe combined immunodeficiency [SCID] due to adenosine deaminase [ADA] deficiency) based on the specificity of the ADA deficiency.
• Ensure the medical record clearly indicates "other" or "atypical" ADA deficiency, or provides details that preclude the use of D81.31.
• Consider sequencing this code as a primary diagnosis when the ADA deficiency is the primary reason for the encounter, or as a secondary diagnosis when it contributes to other presenting conditions.